1. #1

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    Default Pressure Governor Help

    Hello. I am new to the forums and am beginning to learn pump operations. I'm having some difficulty with pressure governors and how they work. Specifically in regard to "pressure" vs. "RPM". What is the difference and when would you want to use one versus the other. 2 members tried to explain it but they contradicted each other, with starting in either, for example setting your pressure then switching to RPM to regulate the pressure like a relief valve. Hope that makes sense and thanks to anyone who can help me out.

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    Default Rpm/psi

    In a nutshell: RPM mode is an electronic throttle only, which regulates the engine speed. If you are in pump, it will increase/decrease your discharge pressure, but will not compensate for lines being opened/closed. Not what you want selected for safety reasons when pumping handlines.

    PSI mode uses a pressure transducer on the discharge side of the pump to tell the electronics how much RPM is needed to maintain a set pump pressure, using the cruise control segment of the engine's ECU. This allows the pump pressure to remain at the set pressure when lines are opened/shut during operations. You should always operate in PSI mode on a fireground with handlines deployed.

    When drafting, you need to start in PSI mode until water is established, because if you start in PSI mode, the safety feature in the governor will sense no water pressure and return the engine to idle.

    I believe Class 1's website (Hale IDEX) has a video clip showing how their electronic governor works.

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    Quote Originally Posted by HFD147 View Post
    In a nutshell: RPM mode is an electronic throttle only, which regulates the engine speed. If you are in pump, it will increase/decrease your discharge pressure, but will not compensate for lines being opened/closed. Not what you want selected for safety reasons when pumping handlines.

    PSI mode uses a pressure transducer on the discharge side of the pump to tell the electronics how much RPM is needed to maintain a set pump pressure, using the cruise control segment of the engine's ECU. This allows the pump pressure to remain at the set pressure when lines are opened/shut during operations. You should always operate in PSI mode on a fireground with handlines deployed.

    When drafting, you need to start in PSI mode until water is established, because if you start in PSI mode, the safety feature in the governor will sense no water pressure and return the engine to idle.

    I believe Class 1's website (Hale IDEX) has a video clip showing how their electronic governor works.

    We just had our delivery class last Saturday on our new engine. Your explanation is almost word for word to what we were told and shown.

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    MODES OF OPERATION

    POWER ON - When the unit is first powered up, the display will show [MODE] and the engine will remain at idle until the mode switch is pressed to select the desired operating mode, PRESSURE or RPM. If the pump is engaged and the OK to Pump LED is illuminated, PRESSURE will be the first mode selected otherwise Throttle will be the first mode.

    RPM MODE - When the unit is in RPM mode, the display will read “THROTTLE” and the green RPM LED will be illuminated. Engine speed is controlled by the INCrease and DECrease switches and the display will indicate “INCREASE” or “DECREASE” as appropriate when these switches are depressed. The governor will maintain the last output signal attained with these switches. The engine will maintain an RPM appropriate for the throttle signal being sent.

    Note: if while operating in rpm mode the pressure increases more than 50 psi from the pressure logged at the last switch press, the governor will limit the pressure increase to no more than a 50 psi differential. The governor may reduce engine rpm to achieve this and the message psi limit will be displayed in the message center. Note: the governor will not attempt to regulate pressure in this mode, only limit the differential pressure to 50 psi from the pressure present when the last switch was pressed.

    PRESSURE MODE - When the unit is operating in the Pressure mode, the display will show “PRESSURE” and the PRESSURE LED will be illuminated. Pump pressure is set by using the INCrease and DECrease switches. The governor will attempt to maintain the last pressure achieved with these switches. The display will indicate “INCREASE” or “DECREASE” as appropriate. The governor maintains pump pressure by controlling engine RPM in response to a signal from the pressure transducer mounted on the pump. When controlling in this manner, the display will show CTRL DEC or CTRL INC. Switching between modes by pressing the mode switch will change the governor from RPM to Pressure mode without a significant change in engine speed or pump pressure. The message center will indicate “PRESSURE” or “THROTTLE” as appropriate once the mode change has been made. When switching to PRESSURE, the pressure set point is whatever pressure is on the transducer at the change.

    PRESET MODE - Pressing the PRESET switch in either mode will control the engine to attain the preset RPM or pump pressure programmed in governor memory. If there is more than 10 PSI pressure on the pump, the RPM Preset is disabled. If the Preset Switch is pressed, DISABLED will be displayed momentarily.

    HIGH IDLE MODE - An input is available to bring the engine speed to a PRESET RPM (High Idle) from a remotely mounted switch. While operating in this mode, the display will show “HIGHIDLE”. This function is inoperative when the pump engaged input is active, there is more than 10 PSI on the pressure transducer or if the MODE switch on the governor has been pressed. Pressing the IDLE switch causes the high idle to drop out and the high idle input must be toggled off and then on again to reinstate high idle. The INC and DEC switches are active in high idle mode and the engine speed can be adjusted, changing engine speed in this manner will not change the preset RPM that is set in memory.

    IDLE MODE - Pressing the IDLE switch at any time returns the engine to idle speed.
    NOTE: A FIRM, POSITIVE SWITCH DEPRESSION IS NECESSARY TO ACTIVATE THIS FEATURE AND A QUICK PRESS MIGHT BE IGNORED.

    CAUTION SENSOR - Whenever the transducer signal is below 0.3 VDC or above 4.8 VDC, a sensor fault will be logged and SENSOR will be displayed in the message center. (SENSOR will flash if the failure occurs while operating in PSI Mode) Once a failure is detected, the governor can no longer maintain a pressure setting. It will hold the current engine RPM and only operate as a throttle. Once the SENSOR message is displayed, it will not clear until power to the governor is reset. It is extremely important that the cause for this message is investigated. The governor cannot control discharge pressure properly unless the sensor signal is reliable and correct.

    SWITCH SESSION PRESSURE - If the INC switch is held the governor will not allow a change greater than 80 PSI without releasing the INC switch and pressing it again. This is only applicable when the pressure is above 90 PSI. This prevents high pressures from being introduced by a distracted operator.

    PRESSURE / WATER LOSS - If the discharge pressure drops below 30 PSI for any reason, engine speed will not be increased. The governor output voltage will reduce to the last known value (engine RPM) where the pressure set point was obtained. The display will flash -INTAKE- during this low pressure condition. If the pressure increases above 30 PSI, OPERATOR will flash and the governor will not increase output unless the operator presses the INC or PRESET switches. If pressure above 30 PSI is not regained within 5 seconds, the governor will return the engine to idle and display LoSupply. The operator must make certain that the water supply is adequate and then reinstate governing using the MODE, INC and/or PRESET switches.

    PRESSURE RECOVERY / CAVITATION (TRIM) - The governor has a trim adjustment, this can be set between 5% and 20% of maximum throttle. This parameter limits the governor’s maximum increase in a pressure recovery attempt. The message center will flash OPERATOR when this limit is reached and the RPM will not increase further. The operator must take positive action to restore discharge pressure. If pressure is not restored within 4 seconds, the governor will reduce output to the last known output where pressure was maintained. The operator must input a new set point with the INC/DEC or PRESET switches. If the pressure rises above the original set point and the governor decreases the engine speed, the governor will resume normal governing operations.

    PSI ENABLE - The pressure governor will not control pressure until a discharge pressure of 70 PSI is attained. It will act as a throttle until this pressure point is achieved.

    RPM PRESET DISABLE - If there is pressure on the pump transducer, RPM Preset is disabled and a DISABLED message will be displayed in the Message Center if you try to use the preset button in the RPM Mode.

    PRESSURE PRESET - While the governor is attempting to reach the preset PSI, the increase is tested at intervals and if the pressure is not increasing, the governor will maintain the engine speed at the point the pressure stops increasing and uses that as the pressure set point.

    HIGH IDLE - The High Idle feature is disabled if there is less than 10 PSI at the pump transducer.

    SWITCH SESSION PRESSURE – If the INC switch is held and the operating pressure is above 90 PSI, the governor will not allow a change greater than 80 PSI without releasing the INC switch and pressing it again. This is to prevent high pressures from being introduced by a distracted operator.

    MESSAGES – OPERATOR will flash anytime the governor can’t achieve a desired pressure.
    This indicates that the governor will not increase engine speed until the pump operator intervenes.
    INTAKE- will be displayed anytime the governor is operating in pressure mode and the discharge
    pressure drops below 30 PSI. If pressure remains below 30 PSI, the display will change to LoSupply and engine speed will be reduced to idle. At this point, the operator must correct the supply or discharge problem and reinstate governing OPERATOR will be displayed anytime the governor can’t achieve a function or pressure. This indicates that the governor will not increase engine speed until the pump operator intervenes. CTRL INC will be flash in the display if the governor cannot regain the set pressure. It will change to OPERATOR (flashing) if pressure cannot be regained within 4 seconds. During these periods, the governor will not command an increase in engine speed and will return to the last known engine speed command where the set point was achieved.

    PUMPING OPERATION EXAMPLES

    OPERATION 1 - Tank Supply for pre-connects or small diameter hose.

    Upon arrival at the scene, position the apparatus and shift into pump gear using department SOP. At the pump panel, the three interlock LED’s must be ON. and the governor Message Center should display [MODE]. If the Throttle Ready Interlock is not present, NO INTLK will be displayed in the message center when the MODE switch is pressed and the governor will not respond to an increase or decrease request. The governor will check for a valid pressure transducer signal at power up, if none is found, SENSOR will be displayed. If this is the case, the governor will operate as a throttle only. It cannot react to pressure changes. The MODE switch must be depressed to select a governing mode.

    Ensure that water is available to the pump by checking the Master Discharge Gauge for pressure. Prime the pump and establish water prior to pressing the governor Preset Switch. Once pressure mode is selected, the PRESET switch may be depressed to quickly bring the pump up to the preset operating pressure. The governor will respond to increase and decrease commands from the INC and DEC switches within the operating capabilities of the engine. When the INCrease switch is pressed, INCREASE is displayed in the message center. When the DECrease switch is pressed, DECREASE is displayed. Whenever the governor adjusts the engine speed to maintain the established RPM, CTRL INC or CTRL DEC will be displayed while the governor is actively adjusting engine speed to maintain the set point.

    The message center will display: THROTTLE or PRESSURE to indicate the current operating mode. Whenever operating with a limited water supply, always be aware of the possibility of running out of water. When the governor is operating in pressure mode it will attempt to recover from a discharge pressure loss and increase engine RPM to compensate. If water is introduced to the pump while the engine RPM is advanced, a pressure spike will result. The magnitude will be a factor of pump speed and water quantity. It is not uncommon to lose water and regain it during operation with extremely low water levels due to the position and configuration of the tank sump.

    OPERATION 2 - Transferring from tank to pressurized water source.

    The transition from tank to hydrant or relay is an operation that needs to be approached with
    awareness. Resultant pressure with no change in pump speed is a combination of the operating
    pressure prior to the change plus the incoming pressurized supply. If operating at 125 PSI and
    adding a 100 PSI pressurized water source, the resultant discharge pressure will be 225 PSI.
    The governor will compensate, but it will not be instantaneous. Any time the pump receives air or
    an air-water mixture, the discharge pressure will drop and the governor operating in pressure
    mode will increase pump speed to maintain the set pressure. Every effort should be made to
    purge or bleed air from the system. When pressurized water hits the impeller, a significant pressure
    spike can occur. This may be an occasion to change the governor to RPM MODE before the
    changeover, establish an adequate supply and then switch back to pressure mode. In some
    instances, a decrease in RPM would be in order and then the PRESET switch can be used after
    switching back to pressure mode to re-establish pressure governing.

    OPERATION 3 - Transferring from tank to draft

    The transition from tank to draft is another scenario that requires a knowledgeable operator/
    engineer. A positive water supply must be established prior to changing the water source. If this
    is not accomplished, the governor will increase pump speed and when the supply is established,
    the pressure will be more than desired. If the engine RPM increases dramatically, press IDLE,
    establish the water supply, press MODE and then PRESET to return to pressure governed
    operation. The total time should be less than 3 seconds.

    OPERATION 4 - Portable Tank (Pond)

    The transition from onboard tank to portable tank is a tank to draft operation. When the portable
    tank is refilled is a time when the pump operator must control the situation. When the tank gets
    low, air can be introduced into the system. The operator must control this so that a pressure
    spike is not introduced. When the tank is refilled from a dump, a wave action can be set up that
    would allow running away from water for a short period of time. This can be controlled by switching to RPM mode temporarily while the tank is refilled.

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    Great explanation. Trying to explain the operation of a pressure governor to students sometimes is not the easiest of explanations. Thanks to HFD for giving me a even easier way to describe it to my students.

    On my engine, a 93' Pierce with a waterous pump, our pressure governor has a toggle switch for increase/decrease and a toggle switch for throttle/pressure. We were told on delivery to start in throttle, get our pressures set and then switch to pressure. I'm not exactly sure why, I wasn't on the job here when we got it, but I've started in pressure and its works the same.

    Our other apparatus is a mix of class 1 and pro-s governors and pressure relief valves.


    HFD...I think you had a typo....but if I am correct you meant to draft you start in RPM.

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    Quote Originally Posted by HFD147 View Post

    When drafting, you need to start in PSI mode until water is established, because if you start in PSI mode, the safety feature in the governor will sense no water pressure and return the engine to idle.

    I.
    Wouldn't that be start in RPM mode

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    Quote Originally Posted by ALSfirefighter View Post
    On my engine, a 93' Pierce with a waterous pump, our pressure governor has a toggle switch for increase/decrease and a toggle switch for throttle/pressure. We were told on delivery to start in throttle, get our pressures set and then switch to pressure. I'm not exactly sure why, I wasn't on the job here when we got it, but I've started in pressure and its works the same.
    Gotta wonder what engine you have in that Pierce. Is it possibly a 2 cycle Detroit (71 or 92 series), mechanically controlled as opposed to electronic. Pierce had be using their "version" of a Barber-Colman governor on some of them, and they're set up with switches just as you describe. There are a number of them in our area. If you look at the control and compare it with the B/C, the only difference is the name on it.

    We have a B/C on our '89 Duplex/Quality. Any time you switch from Throttle mode to Pressure mode or vice-versa, it returns to idle and you have to start over. That's the way B/C designed it to work. I don't know what the Pierce "version" does, but I wouldn't be surprised if it's the same.

    With the electric motor driven primer on our Waterous CMU pump, my practice has been to leave B/C alone until I establish a prime. Then I normally go to Pressure mode and set my discharge pressure. If I was awake enough at the start and put the transfer valve in Volume before priming, I'll switch it back to Pressure at that time also unless I'm in a situation that calls for remaining in Volume. Seems to work quite well.

    Side notes: Even though priming a two stage pump in Volume is considered preferable, I've never had a problem doing it in Pressure. That goes for our '78 Hahn with a Hale QLD 1250 also.

    The Hale originally had a rotary gear primer driven by an intermediate gear in the transfer case. You had to throttle up in order to prime with it. Some years ago the gear primer froze up (a whole 'nother story), so I replaced it with an electric one. Since then, it too primes at idle.

    Stay safe out there, everyone goes home!

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    Default OOPSi

    Good catch by both of you.......it should have read when drafting to start in RPM, then switch over when water is established.

    You both pass my (unintentional) test!

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    Chief:

    Ours when you switch from throttle to pressure does not return it to idle. I will look up the B/C. I know Pierce used everyone else's components with their name on it. I've also have drafted with a 2 stage pump in pressure as well during training. The few times I've done it for fires I've always gone pressure, like as you said due to the gpm's involved in supply. I am all hydrants but commerical/industrial complexes right on a large river, great water supply when needed.

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    You might take a look at Fire Research's website. They have interactive manuals on their website. I prefer their InControl governor as I think it's the easiest to operate and it includes master intake and discharge pressures.

    Check out this link here.
    http://www.fireresearch.com/ietm/FRC.htm

    Click on Interactive Manuals and then the InControl.

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    Quote Originally Posted by toddmcbr View Post
    You might take a look at Fire Research's website. They have interactive manuals on their website. I prefer their InControl governor as I think it's the easiest to operate and it includes master intake and discharge pressures.

    Check out this link here.
    http://www.fireresearch.com/ietm/FRC.htm

    Click on Interactive Manuals and then the InControl.
    I like the layout of the InControl unit very much. But we went with the Pump Boss because the C13 Cat engine runs the newer, faster and much more capable SAE J-1939 data bus. The InControl runs the older J-1587 bus.

    Last time I spoke with anyone at FRC I got the impression that they were not going to upgrade the InControl any time soon. That may have changed by now, but since our engine is nearing completion, we were unable to wait it out. The Pump Boss appears as if it will do a very nice job also.

    Stay safe out there, everyone goes home!

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    Quote Originally Posted by chiefengineer11 View Post
    I like the layout of the InControl unit very much. But we went with the Pump Boss because the C13 Cat engine runs the newer, faster and much more capable SAE J-1939 data bus. The InControl runs the older J-1587 bus.

    Last time I spoke with anyone at FRC I got the impression that they were not going to upgrade the InControl any time soon. That may have changed by now, but since our engine is nearing completion, we were unable to wait it out. The Pump Boss appears as if it will do a very nice job also.

    Stay safe out there, everyone goes home!
    I agree with you on the pump boss. I've used them a few times and I do like them as well. The only draw back is you have to add your (2) 4.5" Master Gauges on the pump panel where as the InControl it is all included.

    Obviously that wouldn't work in your situation and you ended up doing the same thing I would have done if I were speccing out another truck.

    Stay Safe!

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    Any one had any problems with the engine idling down when you open a nozzle? Went interior on a house with an 1-3/4" selectable gallonage nozzle @ 125 gpm, found the bedroom that was on fire, opened the nozzle and it went limp. Im sitting there with the fire starting to roll across the ceiling and a limp nozzle flinging water at it until my E/O runs back to the pump panel (he had been hooking up to the 2nd in engine). Everything turned out ok but we have tried to replicate it with 1-3/4" nozzels, and 2-1/2" nozles but we cant get it to do that. Someone mentioned that the computer in the truck will idle down if it thinks a hose line burst, but like I said we cant replicate it, and there is nothing in the literature from the manufacturer about it. By the way its a Stuphen 1500/1000 with a hale pump.

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    Quote Originally Posted by DelSol View Post
    Hello. I am new to the forums and am beginning to learn pump operations. I'm having some difficulty with pressure governors and how they work. Specifically in regard to "pressure" vs. "RPM". What is the difference and when would you want to use one versus the other. 2 members tried to explain it but they contradicted each other, with starting in either, for example setting your pressure then switching to RPM to regulate the pressure like a relief valve. Hope that makes sense and thanks to anyone who can help me out.

    DelSol,

    The posts by CE11, HFD147, and Tomwnh, been right on!

    CE11,

    I to like the FRC INControl, though I am a bigger fan of the Fire Commander! I also prefer the Detroit over Cat's and Cummings for Governor operations.

    Who is the Pump Boss made by? Never heard of them.

    HFD147,

    Excellent answer in a nutshell.

    Tomwnh,

    I agree with everthing you wrote except for:

    "OPERATION 2 - Transferring from tank to pressurized water source.

    Resultant pressure with no change in pump speed is a combination of the operating
    pressure prior to the change plus the incoming pressurized supply. If operating at 125 PSI and
    adding a 100 PSI pressurized water source, the resultant discharge pressure will be 225 PSI."


    Having worked for the 5+ years now with a Fire Commander I prefer to have it in the Pressure mode for the reason you stated. If you are in the RPM mode operating at 125 PSI and you add a 100 PSI off the hydrant the resultant discharge pressure could be in excess of 225 PSI. Where if you are in the PSI mode the Governor will sense the increase in pressure and drop the RPM's to try and maintain the 125 PSI the Governor was set for. Yes it can only go as far as engne idle, so the guys on the hand line could still see and increase in pressure however it will be far less then the 225+ PSI they would see if operating in RPM mode.

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    [QUOTE=Chief1FF;780518]DelSol,

    Who is the Pump Boss made by? Never heard of them.

    Chief, Pump Boss is a later product of Fire Research Corp. You can see it on their web site. As with InControl and several of their other products, they have an interactive manual available at the site. Check it out!

    Stay safe out there, everyone goes home!

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    Smile Pump Boss

    The "Pump Boss" and the "InControl" are both made by Fire Research Corporation. Interactive manuals are availble for use on the web page at fireresearch.com. or you can go to the bottom of the "Contact FRC" page of the web site, there you can request that a CD be sent to you. It usually takes 4 to 5 days to receive.

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    Default Limp Hose with Governor?

    [QUOTE=oaattx934;780502]Any one had any problems with the engine idling down when you open a nozzle? Went interior on a house with an 1-3/4" selectable gallonage nozzle @ 125 gpm, found the bedroom that was on fire, opened the nozzle and it went limp.

    This has been a frequent problem since we purchased Class 1 governor-equipped Waterous pumps. Our problem is air. If the pressure transducer detects air, it assumes that you are out of water. Even a small amount of air can upset a pump full of water when using a governor. If air is detected, the RPM returns to idle (if operating in PSI mode).

    We teach this method to avoid this problem - always open the TANK TO PUMP valve first, then open the appropriate discharge valves. This gets water moving into the pump and into the hoselines, and removes air from the pump. NOW turn on the governor, and set your PDP.

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    [QUOTE=DelSol;776393]Hello. I am new to the forums and am beginning to learn pump operations. I'm having some difficulty with pressure governors and how they work. Specifically in regard to "pressure" vs. "RPM". What is the difference and when would you want to use one versus the other.

    I have read some good comments in response to this question. I emphatically agree that using PSI mode when changing water supplies is the best method. In my opinion, placing the governor to RPM mode to change the water supply source defeats one of the basic positive features of the governor. Would you set the relief valve prior to changing water supply sources? Of course you would! Why wouldn't you do the same with the governor? Class 1 actually recommends RPM mode in their training video.

    However, just like a pressure relief valve, the governor cannot react instantly. Operate all intake valves slowly - watch your intake and discharge gauges while you open to keep the pressure change smooth. By doing this you help the governor do it's job.

    There are four circumstances where the RPM mode is recommended:

    1. Drafting. You will have great difficulty drafting in PSI mode because of the air. Changing to RPM bypasses the pressure transducer. Once you have successfully drafted, change to PSI.

    2. Charging large diameter hose. If you are pumping a handling at 125 psi (in PSI mode), and now are directed to charge a ladderpipe, opening a large diameter valve will cause a sudden increase in pressure. This is the governor doing it's job, but with dangerous results. The governor will detect the large valve opening as a drop in pressure, and will throttle up quickly to fill the void. This could result in a spike which could overpressure the handline. Change to RPM just long enough to charge the hose and get water flowing, then change back to PSI.

    3. Relay pumping. We direct relay pumping engines (and nurse tankers) to use RPM mode. The attack engine will always be in PSI mode, so all other apparatus pumping to it can use RPM.

    4. Governor problems. We have found the governor to be quirky, mostly due to small amounts of air. If the governor is not cooperating, simply change to RPM mode and bypass the transducer. Get the problem worked out, then switch back to PSI.

    Comments about 1-4?

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    [QUOTE=clifton36;782770]
    Quote Originally Posted by DelSol View Post
    Hello. I am new to the forums and am beginning to learn pump operations. I'm having some difficulty with pressure governors and how they work. Specifically in regard to "pressure" vs. "RPM". What is the difference and when would you want to use one versus the other.

    I have read some good comments in response to this question. I emphatically agree that using PSI mode when changing water supplies is the best method. In my opinion, placing the governor to RPM mode to change the water supply source defeats one of the basic positive features of the governor. Would you set the relief valve prior to changing water supply sources? Of course you would! Why wouldn't you do the same with the governor? Class 1 actually recommends RPM mode in their training video.

    However, just like a pressure relief valve, the governor cannot react instantly. Operate all intake valves slowly - watch your intake and discharge gauges while you open to keep the pressure change smooth. By doing this you help the governor do it's job.

    There are four circumstances where the RPM mode is recommended:

    1. Drafting. You will have great difficulty drafting in PSI mode because of the air. Changing to RPM bypasses the pressure transducer. Once you have successfully drafted, change to PSI.

    2. Charging large diameter hose. If you are pumping a handling at 125 psi (in PSI mode), and now are directed to charge a ladderpipe, opening a large diameter valve will cause a sudden increase in pressure. This is the governor doing it's job, but with dangerous results. The governor will detect the large valve opening as a drop in pressure, and will throttle up quickly to fill the void. This could result in a spike which could overpressure the handline. Change to RPM just long enough to charge the hose and get water flowing, then change back to PSI.

    3. Relay pumping. We direct relay pumping engines (and nurse tankers) to use RPM mode. The attack engine will always be in PSI mode, so all other apparatus pumping to it can use RPM.

    4. Governor problems. We have found the governor to be quirky, mostly due to small amounts of air. If the governor is not cooperating, simply change to RPM mode and bypass the transducer. Get the problem worked out, then switch back to PSI.

    Comments about 1-4?

    Clifton,

    I agree with what you posted!

    Question for you. When you "found the governor to be quirky" I am guessing that you have either a Cummings or Cat engine. I have run in to Detroits with Captain's Governor on them and I did not have this problem, but I have seen what you discribed on the Cat and Cummings engine. What are you running?

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    Red face CAT it is!

    Yes, we use CAT motors exclusively. The engines are Pierce, pumps are Waterous 2-stage 1500 GPM. We have over 30 of them now.
    The Class 1 rep, recognizing the problems we are having, offered some interesting info.

    1. Governors are designed for single stage pumps. He recommends we run them in "volume" at all times, unless we are in a pressure situation. This mimics the single stage pump, and also lowers the pressure at idle, allowing the governor a little more room to work.

    2. He also explained that the Captain is a different device with a CAT engine. I understood there were differences in the wiiring and programming, but I didn't think the CAT-Class 1 combo was part of the problem.

    A Waterous rep told me they lean toward Detroit and FRC governors, after explaining our problems. Of course Class 1 built by IDEX/Hale is their main competitor, but I got the impression that the Captain governor was not his favorite. Some have actually recommended a return to relief valves due to the problems we are having, but when the engineer fully understands the governor, and knows how to overcome the "quirks" the pumps do their job very well. And the CAT is remarkably reliable.

  21. #21
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    Default Rpm/psi

    I disagree with point #3. Unless the operator is highly trained and knows exactly what to do at all times, I wouldn't recommend being in a relay in RPM. Once set, this will not allow the unit to react to "running away from water" which typically is caused by the source pumper losing some or all of its supply. In PSI, the governor is programmed to return to idle if this condition develops, avoiding costly pump damage from cavitation. This should be covered in the operator's manual. Operating anything outside of manufacturer's recommendations could be dangerous, and could void warranty claims.

    Just be sure everything you are doing is according to accepted practice and you should be OK.

  22. #22
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    Default Throttle or Pressure mode?

    There's good logic to both sides of Throttle mode or Pressure mode question, HFD, but on the balance, I lean toward pumping relay in Pressure, partly for the reasons you give. The argument that has been advanced for pumping in Throttle mode is that in Pressure mode, under some conditions, a "hunting" situation could begin. That's where one engine reacts to a change, then the next one reacts and so on down the line. Supposedly you wind up with everyone is out of sync with one another. The few times that I've been in relays like that and we were all in Pressure mode, that didn't occur. The units responded to changes at the nozzles and all worked well.

    Stay safe out there, everyone goes home!

  23. #23
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    Default Pressure govenors

    I have to highly disagree with the point of being in "Pressure" mode when being anyone but the attack pumper in a relay operation. My department and many other departments experienced complete pump shutdowns when using our pressure govenors (they all operate the same so the manufacturer will not be mentioned here). ALL P/Gs will shut down when they experience a sudden 30 PSI drop in about a 10 second time period on the intake side of the pump. We complained to the manufacturer, but he kindly noted in our manual, that P/G 's are designed to do that, and that the manual states the ONLY pumper that should be in "Pressure Mode" is the attack pumper, as all other pumpers in a relay, especially if you use LDH, will have major pressure fluctuations. Also, you can have all the bleeder valves in the world on a LDH intake, and it will still not take all the air out of the system. The sensors can read LOW INTAKE PRESSURE and shut the pump down. This occured no less than 4 times during fires when we had interior attack crews on the end of the hoseline. Add to this the fact we use automatic nozzles, and it could lead up to a very disasterous ending as the members will not know they have a major pressure loss.
    Another instance the operator opened his Tank Fill to refill his water tank after the initial attack was made with tank water. The rig was made in 2006, so it has a 2" pipe back to the tank. Do the math. That is 1000 GPM. The P/G read cavitate, and the pump shut down. Luckily our pump operator was right on it.
    The answer to this is training. If you are in MODE/PRESSURE, and experience a pressure loss, take the P/G out of MODE/PRESSURE and operate in MODE/RPM and throttle back up.

    Keep the attack pumper in PRESSURE, all others in RPM. That is especially MANDATORY with drafting. I have a better idea...go back to Vernier throttles and standard relief valves and lets do away with this bad experiment all together!
    Stay Low
    ROOFMAN

  24. #24
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    Default

    Quote Originally Posted by Rescueruss View Post
    I have to highly disagree with the point of being in "Pressure" mode when being anyone but the attack pumper in a relay operation. My department and many other departments experienced complete pump shutdowns when using our pressure govenors (they all operate the same so the manufacturer will not be mentioned here). ALL P/Gs will shut down when they experience a sudden 30 PSI drop in about a 10 second time period on the intake side of the pump. We complained to the manufacturer, but he kindly noted in our manual, that P/G 's are designed to do that, and that the manual states the ONLY pumper that should be in "Pressure Mode" is the attack pumper, as all other pumpers in a relay, especially if you use LDH, will have major pressure fluctuations. Also, you can have all the bleeder valves in the world on a LDH intake, and it will still not take all the air out of the system. The sensors can read LOW INTAKE PRESSURE and shut the pump down. This occured no less than 4 times during fires when we had interior attack crews on the end of the hoseline. Add to this the fact we use automatic nozzles, and it could lead up to a very disasterous ending as the members will not know they have a major pressure loss.
    Another instance the operator opened his Tank Fill to refill his water tank after the initial attack was made with tank water. The rig was made in 2006, so it has a 2" pipe back to the tank. Do the math. That is 1000 GPM. The P/G read cavitate, and the pump shut down. Luckily our pump operator was right on it.
    The answer to this is training. If you are in MODE/PRESSURE, and experience a pressure loss, take the P/G out of MODE/PRESSURE and operate in MODE/RPM and throttle back up.

    Keep the attack pumper in PRESSURE, all others in RPM. That is especially MANDATORY with drafting. I have a better idea...go back to Vernier throttles and standard relief valves and lets do away with this bad experiment all together!
    Stay Low

    Rescue,

    Question for you, do you run either Cat or Cummings engines?

    I am also going to guess you have Captains Governor!

    You are correct that the answer to the problem is training! The tendenceny in today world is to believe that anybody can run a pump with a governor on it. When in fact you still need to have some one at the pump that knows what they are doing!

  25. #25
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    Default Pressure Governor answers

    I am the North East Regional Manager for Fire Research Corporation. All of the information that is provided in this post will be specific to the Fire Research product line. How ever the basic theory of operation for any pressure governor is the same, but each manufacture uses their own concept, formulas and values to make the governor function. My descriptions are based on the governor being in “PRESSURE” mode unless other wise stated.

    The first thing that I will address is a 2 stage pump. A pressure governor does not know if a pump is a single stage or a multi stage pump. The pressure governor will increases or decrease the engine RPM to maintain the discharge pressure that is selected by the operator. The discharge pressure is supplied to the pressure governor by the discharge pressure sensor in the form of an analog electrical signal that changes proportional to discharge pressure in the pump. The pressure transducer if correctly installed will be in the discharge manifold of the fire pump. Some fire pump manufacturers provide a port in their casting for the main discharge pressure gauge line or transducer. There are some advantages for operating a two stage pump in volume that will affect the performance of a pressure governor. The first is when operating with a high intake pressure if the transfer valve is in pressure/series mode the discharge pressure at idle will be higher thus decreasing the window of operation for the governor. The second advantage to operating in volume/ parallel mode is the engine RPM’s will increase more to accomplish the same pressure change compared to operating in pressure/series. This provides for a little better resolution for the governor’s control. How ever an operator will probably not be able to tell a difference anyway.
    The next thing to discuss is the pressure transducer detecting air in the pump. A pressure transducer can not detect air. The pressure governor reacts to air in a pump because a fire pump is a centrifugal pump which means it can not pump air. If air is introduced into a pump the discharge pressure in the pump will drop and the governor will increase the engine speed attempting to maintain the discharge pressure selected by the operator. The pressure governor will not drop to idle from a small amount of air in the pump. If the water supply is not sufficient for the amount of water that you are trying to discharge and the discharge pressure drops below 45 PSI the pressure governor will limit the engine speed to a 1100 RPM’s, if the pressure drops below 15 PSI the engine will be returned to idle. If a water supply is reestablished and the discharge pressure rises above 45 PSI the governor will increase the engine RPM and return to the pressure selected by the operator.
    The pressure governor does not monitor the intake pressure of the fire pump so a rapid 30 PSI change on the intake pressure would only be detected by the governor because as a result of the intake pressure changing the discharge pressure will drop. If the governor will increase the engine RPM to return the discharge pressure to the pressure selected by the operator. This is assuming that the discharge pressure did not drop below 45 PSI.
    The reason that it is recommended to establish a draft in “RPM” mode is to reduce rapid changes in the engine RPM by the governor due to air pockets in the hard suction and pump. After you have established your prime and have a steady flow of water from the pump it is recommended that you switch to “PRESSURE” mode and allow the governor to do its job.
    When switching the water supply source from tank to hydrant, draft to hydrant, or draft to relay, water flow through the pump can become turbulent and the positive pressure from these sources may generate a sudden pressure surge. It is recommended that the governor be set in “RPM” mode before changing the water supply source. After you have completed changing your water source, switch back to “PRESSURE” mode of operation.
    When relay pumping or charging a large diameter hose with water it is recommended that the pressure governor be operated in the “PRESSURE” mode. If you are operating in “RPM” mode you have very limited pressure protection and the operator must manually control the pump to protect against water hammers and maintain a consistent discharge pressure. If your pressure governor is dropping to idle when you charge Large Diameter Hose you may be opening your discharge valve too rapidly and the pump discharge pressure is dropping below 45 PSI. Open your valve a little slower and do not open the valve completely until the hose is completely full of water. (This will also protect your hose from damage caused by a water hammer.)

    I hope the information that I have provided has answered some questions. If you would like additional information about the operation of a Fire Research product feel free to e-mail brianr@fireresearch.com. Please provide a way for me to contact you. You can also post your question here and allow others to learn the answer to your question as well. Additional information is available from our web page fireresearch.com.

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