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  1. #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.


  2. #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!

  3. #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

  4. #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!

  5. #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.

  6. #26
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    Default

    Brian - Thanks very much for your clear explanation of the whats and whys of how your pressure governors work. My only comment refers back to one I made in an earlier post; that is, since our primers are electric motor driven, they operate completely independently of the vehicle engine. I get a prime before selecting anything on the pressure governor. Once I have my prime, I select "Pressure (usually) and ramp up to my desired discharge pressure.

    Understand, of course, that I'm using a Barber Colman unit on a mechanically controlled Detroit 6V. It doesn't default to anything. You have to select either "Pressure" or "RPM" to get anything out of it. Otherwise it does nothing at all. Also, by its design, if you change modes it goes back to idle and you have to ramp up again. I understand that newer units such as FRCs do not do that.

    From going through the Interactive Training Module for the "Pump Boss" on the FRC web site, I gather that even though it defaults to "Pressure" mode when you engage the pump, you won't immediately get a pump runaway condition. So for that reason, I wonder why I wouldn't want to just accept the default setting, establish my prime, then ramp up from there.

    Also, we deal with exceptionally high hydrant pressures. When switching from tank supply to hydrant supply, having the governor in "Pressure" mode allows it to drop the engine RPM to more closely represent what's needed to maintain the desired discharge pressure. I'm assuming and hoping that the FRC unit, when we receive it, will do the same thing.

    Any comments or corrections?

    Stay safe out there, everyone goes home!

  7. #27
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    Default operating in Pressure Mode

    Chiefengineer11,
    The PumpBoss has "Running Away From Water" protection that will not allow the engine rpm to increase more than 300 rpm with out an increase in the discharge pressure. This will take care of most of the possible problems of astablishing a prime from draft or changing your water source while in "Pressure Mode". The most important thing to remember is to bleed all of the air out of the supply line before opening the intake valve to the pump.

  8. #28
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    Default Pump Boss

    Thanks for the additional info, Fixer. I'm understanding that when I go from Road to Pump, the unit will default to Pressure and Idle. Am I also right in assuming that if no additional throttle is called for, the engine will remain at idle until the system sees a request for more? If so, I don't see a problem. I should be able to get a prime, then begin ramping up to the desired operating pressure.

    Stay safe out there, everyone goes home!

  9. #29
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    Default

    Quote Originally Posted by Firefixer View Post
    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.
    I'm a little confused. You are saying to set the governor to RPM mode, thereby eliminating the pressure regulating effect of the device at a transition point that requires pressure control to keep from damaging equipment and knocking firefighters off their feet. Can you explain more? NFPA has allowed pressure governors in place of relief valves. By setting to RPM mode and having no relief valve, you have NO discharge relief protection. We run our handlines at 110 and 120 PSI usually. When the 100 PSI from a hydrant hits the pump thats already spinning 110 PSI to the handline, thats going to cause a discharge pressure of around 200 PSI. Thats dangerous unless theres regulation by the pressure control device. We train all of our operators to leave it in pressure mode when making that transition so that the governor can kick the engine speed down once more pressure is detected from the hydrant pressure.

  10. #30
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    Default operating in Pressure Mode

    chiefengineer,
    You are correct, when the governor is engaged it will always default to pressure mode. The engine RPM will remain at idle, the governor does not become active until a command is supplied by the operator by pressing the preset button or turning the control knob on the PumpBoss. If the ProS or Incontrol are used you have to press the Preset, Increase or Decrease button.

    MG3610,
    The PROS and the INCONTROL pressure governors have two stages of cavitation protection, the "No Water" and "Low Water" modes. Neither of these would prevent the pressure governor from increasing the engine RPM if air is introduced into the pump while switching water supplies. This can happen when you do not bleed the air from the supply line prior to opening the intake valve. The air in the pump will cause the pressure governor to increase the engine RPM while it attempts to maintain the pressure selected by the operator. When the air makes its way out of the pump and into the discharge line the water from the intake fills the pump which is know spinning very fast. This could cause a pressure spike.
    The PUMPBOSS governor has a third stage of protection called “Running Away From Water”, this will prevent the engine RPM from increasing more than 300 RPM with out an increase in the discharge pressure.

  11. #31
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    Default

    Quote Originally Posted by Firefixer View Post
    chiefengineer,
    You are correct, when the governor is engaged it will always default to pressure mode. The engine RPM will remain at idle, the governor does not become active until a command is supplied by the operator by pressing the preset button or turning the control knob on the PumpBoss. If the ProS or Incontrol are used you have to press the Preset, Increase or Decrease button.

    MG3610,
    The PROS and the INCONTROL pressure governors have two stages of cavitation protection, the "No Water" and "Low Water" modes. Neither of these would prevent the pressure governor from increasing the engine RPM if air is introduced into the pump while switching water supplies. This can happen when you do not bleed the air from the supply line prior to opening the intake valve. The air in the pump will cause the pressure governor to increase the engine RPM while it attempts to maintain the pressure selected by the operator. When the air makes its way out of the pump and into the discharge line the water from the intake fills the pump which is know spinning very fast. This could cause a pressure spike.
    The PUMPBOSS governor has a third stage of protection called “Running Away From Water”, this will prevent the engine RPM from increasing more than 300 RPM with out an increase in the discharge pressure.
    OK. So if proper etiquette and tactics are followed and the air is bled (as it very well should be) then the governor staying in pressure mode is the safest way to protect the discharges from the spike of the incoming water pressure. You kind of only half answered my question.

  12. #32
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    Cool Governor Woes

    This thread has certainly highlighted a problem - pump governors are complicated, and require a considerable amount of training - More training than any other pump component or accessory.

    I remember when I first learned about pressure relief valves. It took about 15 minutes to become comfortable with it.

    When a pressure relief valve fails on scene, we lose pressure protection and the engineer has to be more vigilant. When a governor fails (or reacts wildly to the presence of a small amount of air) we could potentially lose discharge pressure entirely. Which situation are you more "comfortable" with?

    And I will continue to change from tank water to hydrant water in PSI mode.

  13. #33
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    Default

    Quote Originally Posted by clifton36 View Post
    This thread has certainly highlighted a problem - pump governors are complicated, and require a considerable amount of training - More training than any other pump component or accessory.

    I remember when I first learned about pressure relief valves. It took about 15 minutes to become comfortable with it.

    When a pressure relief valve fails on scene, we lose pressure protection and the engineer has to be more vigilant. When a governor fails (or reacts wildly to the presence of a small amount of air) we could potentially lose discharge pressure entirely. Which situation are you more "comfortable" with?

    And I will continue to change from tank water to hydrant water in PSI mode.
    Clifton,

    I agree with you on several of your points!

    I would rather have a pressure governor over a relief valve any day. Why? Because the relief valve is probably the most ignored piece of equipment on a pump. Most operators of pumps (Lever Puller/Button Pusher not true pump operators) have no clue what a Relief valve is or what it does.

    Training on a Governor is a must! It also makes sure that the person operating the pump has pressure protection on the hand lines that most likely would not be there if the pump was equipped with a relief valve. Most departments do not train there drivers/operators in the proper use of the Governor.

    As for switching from tank water to hydrant water could not agree with you more, PSI mode is the way to go.

  14. #34
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    Default

    Chief:

    Within my FD I am a huge proponent of the pressure governor. Just the fact that it can maintain the set pressure (corrects a pressure drop as well as a spike) makes it better than a relief valve. You also don't have to reset it after every change in flow. It appears that our problems (other than training 300 engineers) are related to the Class 1/CAT combo, and FRC and Detroit deserve a hard look.

    The recommendation by FRC and Class 1 of changing water supply sources in RPM mode points out a major flaw in the syetm - the sensitivity to air. They need to be more straightforward with this issue (and maybe they are in some cases, but we had to figure this out ourselves).

    And you are correct about the relief valve being ignored. But the primary reason they are ignored in my department is the fact that 75% of them don't work. They are Hale TPM valves, and the high sediment in our water supply requires rebuilds every 6 months. Our shop can't keep up, which is the primary reason for the switch to governors. We purchased governor equipped engines in 1991 (Waterous pumps with Detroit governors) and in 1994 (Godiva pumps with a no-name crap governor). In between we always buy relief valve equipped pumps, so we are constantly re-training. If we stick with ONE type of pressure relief system, buy one that works, train the engineers, and maintain the system we wouldn't have a problem now.

    I have gained some good information from this thread. Thanks for all the replies to my posts.

  15. #35
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    Is it just me or does it now seem like Class 1 and FRC have their heads a little buried somewhere dark? One of the main points of a pressure governor (especially if being used in place of a relief valve) is to regulate pressure. Both have advocated not using the pressure regulating feature at crucial times of need (aka switch to hydrant from tank water).

    Our 1994 KME's have the Detroit 8V92TA engine with a class 1/detroit governor. The pump intakes have air controlled butterfly valves. When you flip that switch, lookout.....here comes the surge. Without the governor in PSI mode, you would launch the nozzleman!! We have trained quite a bit on them and always had success with the PSI mode controllign that huge surge from the switchover. Interestingly enough, these 2 rigs also both have Hale TPM relief valves. The major issue here is that in PSI mode the governor tries to fight the relief valve and race the engine when it opens. Works fine in RPM mode though.

    I'm starting to think we would be beter off going back to vernier throttles and discharge relief valves.

  16. #36
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    Default

    First of all, air actuated intake valves do not meet the NFPA requirement for minimum of 3 seconds from full closed to full opened. Not sure why you have these valves on your apparatus, but sounds like they should have been electric actuated in this application.

    Don't give up on the governors, they really do work better than throttle/relief valves. The usual reason for these statements is lack of information, or lack of willingness to embrace new technonlgy. Its not as complicated as some try to make it. Do your homework, and base your position on FACT, not EMOTION!

  17. #37
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    Default Just the FACTS

    Quote Originally Posted by HFD147 View Post
    First of all, air actuated intake valves do not meet the NFPA requirement for minimum of 3 seconds from full closed to full opened. Not sure why you have these valves on your apparatus, but sounds like they should have been electric actuated in this application.

    Don't give up on the governors, they really do work better than throttle/relief valves. The usual reason for these statements is lack of information, or lack of willingness to embrace new technonlgy. Its not as complicated as some try to make it. Do your homework, and base your position on FACT, not EMOTION!
    You are incorrect. NFPA allows air actuated valves for intakes. Current technology allows for adjustment of opening speed. In 1994, when these standards were different, alof of todays requirements werent applicable. We also have 4 3" discharges with regular ball valves and swing handles.

    16.6.4 of 1901 (2003) says the intake valve must be slow open/slow close referenced in 3.3.152 as any valve that opens from the fully closed to fully open position in no less than 3 seconds and vice aversa. I assume that wasnt required in 1994, as the style air valves we have are common on many rigs I have seen.

    Akron's air valves are NFPA compliant. http://www.akronbrass.com/pages/akro...actuators.html

    I will agree that the choice to select air valves was poor at best. Live and learn.

    I see what you are saying about not understanding somethign and givign up on it, but thats not the case here with me. I am frustrated because 2 manufacturers state to use the device in a manner which makes it effectively useless at a crucial transition point. Makes alot of sense huh???

  18. #38
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    Default

    OK, you're right about the standards in 1994 vs. today. My air actuated intake valve comment was based on our experience, but is due to excessive hydrant pressure. If you "detune" the air actuator to compensate for speed, you lose the torque required to allow the valve to open under pressure. At any rate, in my opinipon the only intake valve suitable for air actuators is the tank-to-pump. The rest should be electric or manual handle or gear actuated handwheel control. The air valves are too hard to get to operate the right way for every application.

    As far as the pressure governor issues between PSI and RPM, we just haven't experienced the issues some others have in this thread. Lucky? Hope so. But ours have been working fine for 10 years now, and we wouldn't hesitate to buy one again next time.

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