1. #1
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    Default Governor RPM mode

    Searched for this info but didn't find it so here goes..

    We're stepping up from straight old mechanical "engineer controls the pressure" pump control to a FMC pump boss. Why are there both a Pressure and an RPM mode? Seems like w/ the pressure mode ('specially w/ the preset feature) you dial it in and away you go?

    TIA,

    DevaE2

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    RPM mode simulates the old fashioned pump throttle. Up and down and thats where it stays until you adjust it.

    PSI mode will maintain the PUMP PRESSURE. It has no sensors or effect on INDIVIDUAL DISCHARGE PRESSURE. If you set it for 130, it will maintain 130lb on the pump's master discharge gauge. If you are running one handline that happens to need 130 at the line discharge, you are golden. But when you have multiple lines that operate at different pressures, you still need to play the gate game and do your job.

    The preset button is just that. A preset PSI. It may or may not be what you want. The PSI you actually require is dependent on how many lines, how long they are, what nozzles are in use, etc etc.
    Even the burger-flippers at McDonald's probably have some McWackers.

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    Got it - thanks so much.

    DevaE2

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    FRC has some good interactive programs for their products that will help you understand them better.

    http://www.fireresearch.com/governors.php

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    Cool

    Eh! Welcome to the 21st century

    Kidding of course.

    As you get used to the pressure side, keep in mind that even a simple evolution like refilling your tank can get pretty exciting if crews are working off your truck. Open up the tank fill / recirc valve and you've essentially created a loop that the governor will try and pressurize. The pump will speed up to try and maintain pressure... and of course it will fail because there is an open loop.

    Two ways around this- don't open the tank fill too far... (sometimes not an option) and / or a brief switch to RPM mode.

    Another problem we've run into is hitting the preset before the hose is fully charged. One of the problems we ran into when we got the transverse lines out really fast and ready for water before the pump was fully primed (in cold weather it's often dry... an argument for another time). The tank supply is pulled and unless the operator makes a concerted effort to remember not to hit the preset out of habbit... hitting it in PSI mode will again force the pump to race to boost pressure- of course it's trying to boost either half a hose full of air or a pump that's still similarly afflicted.
    Ian "Eno" McLeod

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    Quote Originally Posted by Eno305 View Post
    Eh! Welcome to the 21st century

    Kidding of course.

    As you get used to the pressure side, keep in mind that even a simple evolution like refilling your tank can get pretty exciting if crews are working off your truck. Open up the tank fill / recirc valve and you've essentially created a loop that the governor will try and pressurize. The pump will speed up to try and maintain pressure... and of course it will fail because there is an open loop.

    Two ways around this- don't open the tank fill too far... (sometimes not an option) and / or a brief switch to RPM mode.
    On our new engine, the tank fill lines are so huge (I think two 3" pipes maybe), that opening the tank fill all the way will cavitate the pump. It is so wide open, the pump can't maintain pressure and just runs itself dry trying. As a result, we only open the tank fill about 1/2 way.
    Even the burger-flippers at McDonald's probably have some McWackers.

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    Quote Originally Posted by Eno305 View Post
    Eh! Welcome to the 21st century

    Kidding of course.

    As you get used to the pressure side, keep in mind that even a simple evolution like refilling your tank can get pretty exciting if crews are working off your truck. Open up the tank fill / recirc valve and you've essentially created a loop that the governor will try and pressurize. The pump will speed up to try and maintain pressure... and of course it will fail because there is an open loop.

    Two ways around this- don't open the tank fill too far... (sometimes not an option) and / or a brief switch to RPM mode.

    Another problem we've run into is hitting the preset before the hose is fully charged. One of the problems we ran into when we got the transverse lines out really fast and ready for water before the pump was fully primed (in cold weather it's often dry... an argument for another time). The tank supply is pulled and unless the operator makes a concerted effort to remember not to hit the preset out of habbit... hitting it in PSI mode will again force the pump to race to boost pressure- of course it's trying to boost either half a hose full of air or a pump that's still similarly afflicted.
    The governor will fail only if the tank to pump line isnt sufficient to supply the rate you are trying to circulate tank water. Opening a 2 1/2" ball valve (tank fill line) all the way discharges a substantial amount of water. Can't see any reason why youd circulate your water with the TF line all the way open anyway. Expect about 500 GPM from a single 3" TTP line and somewhere around 1000 GPM for a single 4". Opening the tank fill line all the way is also unnecessary in most cases when refilling the tank if you are operating other lines. Some tank manufacturers limit the pressure at which a tank can be refilled as well. In some cases its max 100 PSI.

    You can see the same result by opening any other pump discharge until youve maxed out the TTP line flow capability and the pump cavitates.

    The issue isnt an "open loop" its that you are trying to pump more water than than can enter the pump, causing cavitation and an appropriate response by the governor to maintain the pressure then revert to its "safe mode" to limit damage to the pump.

    RPM modes arent quite that simple either. As quoted from Fireresearch Pump Boss

    RPM Mode Operation
    In the RPM mode of operation the RPM LED is on. The governor maintains a
    constant engine RPM.
    The pump discharge pressure can vary but, as a safety feature, the governor limits
    the increase in pressure to 30 PSI over the last established PSI value. As the discharge
    pressure approaches this limit the governor automatically lowers the RPM to prevent
    a high pressure surge. The RPM LED blinks as the governor sets a lower RPM. This
    lower RPM will be the new operating RPM setting.
    Note: When changing from pressure to RPM mode during operations, hold
    the RPM button for 3 seconds. The RPM setting is the RPM that the pump
    was operating at in pressure mode.
    1. Press RPM button to select RPM mode.
    Result: RPM LED goes on.
    2. Press PRESETand/or rotate control knob to select RPM setting.
    Result: Message display shows RPM setting, engine RPM changes.
    3. Press IDLE button after operations to bring engine to idle RPM.
    Result: Message display shows IDLE ENGINE, engine at idle RPM.

    Other brands also have specific variables that make them not so simple.

    Read the operators manual.
    Hale/Class 1: http://www.class1.com/Main/Content,22,35.aspx
    Fire Research: http://www.fireresearch.com/governors.php
    Last edited by MG3610; 07-21-2009 at 10:03 AM.

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    Quote Originally Posted by MG3610 View Post
    Reading the manual is always encouraged.

    But sometimes you need to play around with things a bit before they sink in. Here's a link to the IETMs (Interactive Electronic Technical Manuals), click the image with the green PLAY arrow to launch the IETM (this opens in a new window), click to accept the personal responsibility agreement, then click "Skip to Catalog Main menu" (unless you want to run through a quick scenario to see what an IETM is like first).

    You can run an interactive for any of five of our pressure governors.
    http://www.fireresearch.com/frcnews/ietm

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    And in PSI mode you can get wide fluctuations in pressure if you have a incoming feed line particularly from another pumper or nurse tanker.Better to use rpm in those instances. T.C.

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    Quote Originally Posted by nmfire View Post
    RPM mode simulates the old fashioned pump throttle. Up and down and thats where it stays until you adjust it.
    There's one difference between the old traditional throttle controls and the RPM mode. With the old throttle controls, as you added or shut down lines, the engine speed would decrease or increase with the load subtracted from or added to it. In RPM mode on the new controls, the RPM stays exactly where you set it. To a little extent then, it compensates for the change in load against the engine, but it does not maintain pressure as Pressure mode does.

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    Again,

    Thanks for all the links as well as personal observations. Reading the manual is always a good thing - as long as there is a manual. We have this engine on "Long Term Loan" from a shutdown federal project.

    Thanks,
    DevaE2

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    Quote Originally Posted by Rescue101 View Post
    And in PSI mode you can get wide fluctuations in pressure if you have a incoming feed line particularly from another pumper or nurse tanker.Better to use rpm in those instances. T.C.
    This is the main reason the pressure governor has value in PSI mode. I'm confused why you suggest to run RPM mode in these situations. Also, most pumps on the market today (unless its a CAF pump) are built with only a pressure governor and no discharge relief valve. With the governor in RPM mode you are negating most of the pressure protection in the pump and are limited to the relief protection of the pump relief valve on the pump body (whatever its set to) and the suction inlet relief valves.

    Just wondering, seems kind of contrary to everything I've ever learned or taught people.

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    Had a structure fire in a neighboring town.Attack Engine was set on PSI being fed by a 3000 gallon Pumper/tanker thru a 4" line.Everytime the attack Engine "sensed"an incoming fluctuation it went to dead idle.Damn near burned up two interior crews.Might have been a bad sensor,I don't know.I switched the Attack to RPM,problem went away,we put the fire out and went home.Still comes down to a skilled Pump operator,which are getting scarcer.

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    Quote Originally Posted by Rescue101 View Post
    Had a structure fire in a neighboring town.Attack Engine was set on PSI being fed by a 3000 gallon Pumper/tanker thru a 4" line.Everytime the attack Engine "sensed"an incoming fluctuation it went to dead idle.Damn near burned up two interior crews.Might have been a bad sensor,I don't know.I switched the Attack to RPM,problem went away,we put the fire out and went home.Still comes down to a skilled Pump operator,which are getting scarcer.
    That sounds like a sensor or computer problem. When we got our Barber-Colman governor in '89, I was concerned about how it would function in a relay where the same or other governors were in use. It was many years until such a situation presented itself, but when it did, all the different governors in the relay worked well.

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    Couldn't rule that out Sam,wasn't my rig.I just know it didn't work and took the necessary steps to complete the operatiion. In talking to other operators in other places,I'm going to suggest to you that this is NOT an uncommon happening. T.C.

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    Ah, yea that is definately not what it is supposed to do. In fact, it should be just the opposite. It is supposed to nicely make up for those little fluctuations. The only time it should give up and go back to idle mode is if the incoming supply drops so low that it can not maintain pressure.
    Even the burger-flippers at McDonald's probably have some McWackers.

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    Quote Originally Posted by Rescue101 View Post
    Had a structure fire in a neighboring town.Attack Engine was set on PSI being fed by a 3000 gallon Pumper/tanker thru a 4" line.Everytime the attack Engine "sensed"an incoming fluctuation it went to dead idle.Damn near burned up two interior crews.Might have been a bad sensor,I don't know.I switched the Attack to RPM,problem went away,we put the fire out and went home.Still comes down to a skilled Pump operator,which are getting scarcer.
    If the operator supplying the attack engine was operating his controls haphazardly, thats a possibility in the issue.

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    Nope,steady feed within normal Engine to Engine.And this isn't the only one I've heard of even though it's the first I actually personally experienced.So either we've got a batch of bad sensors around or the control isn't as precise as you guys think it is. As long as I can fix the problem by changing mode,I'm ok with that.Over the years been a lot of little hurdles thrown at us by various pumps.But losing water pressure to interior crews is one I WON'T tolerate. T.C.

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    Quote Originally Posted by Rescue101 View Post
    Nope,steady feed within normal Engine to Engine.And this isn't the only one I've heard of even though it's the first I actually personally experienced.So either we've got a batch of bad sensors around or the control isn't as precise as you guys think it is. As long as I can fix the problem by changing mode,I'm ok with that.Over the years been a lot of little hurdles thrown at us by various pumps.But losing water pressure to interior crews is one I WON'T tolerate. T.C.
    On our HME, the governor will look for a cavitation and shut down to "protect" itself / pump. (Hale Qmax 2000gpm) I was told that if drafting or not having a very steady supply may make it sense a cavitation so we should run in rpm mode until we made sure everything was flowing correctly. (Even from an air leak on the intakes.

    Like most things, little things will bite you. If the computer sees it once (governor) it saw it so it shuts down as programmed. These controllers are NOT able to do what a trained pump operator / engineer can figure out.

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    Kinda what I was alluding to.I think it MAY have been a sensor problem but the crews safety trumps whatever little safety hazard may be created by running it in RPM by an experienced D/O. T.C.

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    Quote Originally Posted by Rescue101 View Post
    Kinda what I was alluding to.I think it MAY have been a sensor problem but the crews safety trumps whatever little safety hazard may be created by running it in RPM by an experienced D/O. T.C.
    TC

    I have my sources that say it is not your first time at the dance... (Not just the observations on here but people in New England....)

    In fact, one of the sources was the person that explained the pressure vs. rpm mode to me. The other posts on here from time to time and tweeks you.

    I work for Big Blue in a maintenance group and see computers and sensors behaving poorly pretty regularly. People must understand and want to understand more on how things work and don't work. The electronic age of controlling vehicles is here and you probably will not see it go back. When lives are on the line, you can't just say I pushed the button and it did not work... you need to know the signs and recognize it is time to get plan B in motion...RIGHT NOW.

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    Agreed.But this curiousity factor seems to be waning.At the time,the need to get water to the attack crews was a higher priority than checking sensors.So I did what needed to be done for that to happen.Wasn't my rig so I don't know what was found on inspection post incident.In talking to others with similar systems,several have experienced similar problems. So isolated,it isn't.Applying the KISS principle,train and test with your equipment often.Know what it does when you do various operations.But know that you CAN use RPM mode when all else fails.And everybody will still go home. T.C.

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    Quote Originally Posted by Rescue101 View Post
    Agreed.But this curiousity factor seems to be waning.At the time,the need to get water to the attack crews was a higher priority than checking sensors.So I did what needed to be done for that to happen.Wasn't my rig so I don't know what was found on inspection post incident.In talking to others with similar systems,several have experienced similar problems. So isolated,it isn't.Applying the KISS principle,train and test with your equipment often.Know what it does when you do various operations.But know that you CAN use RPM mode when all else fails.And everybody will still go home. T.C.

    TC,

    I think you hit the nail on the head! Training, Training, and more Training!!! Then train some more! With all the electronics that are on the apparatus today we do not train the operators to know what to do when something goes wrong, or how to over come a problem! The sensors used on the governor's today can pick up dirt and debris, which can affect the operation of the governor's. I have also found also (after replacing the sensor for the third time in a period of a year) that you should operate your pumps on a weekly basis at a minimum to prevent this from happening. I know of several manufacturers that have moved the sensor from the pump (pressure side) to a remote location to take care of some the “wide fluctuations in pressure” that where occurring while in pump operations.

    Mark

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    Quote Originally Posted by Rescue101 View Post
    Had a structure fire in a neighboring town.Attack Engine was set on PSI being fed by a 3000 gallon Pumper/tanker thru a 4" line.Everytime the attack Engine "sensed"an incoming fluctuation it went to dead idle.Damn near burned up two interior crews.Might have been a bad sensor,I don't know.I switched the Attack to RPM,problem went away,we put the fire out and went home.Still comes down to a skilled Pump operator,which are getting scarcer.
    Was the tanker in PSI mode? I know every brand is different, but Class1 recommends that the source rig be in RPM mode. This doesn't sound like the case, but two rigs in PSI mode will "chase" each other and they react to each other's changes. Also, Class1s are set to warn of a low supply when incoming pressure drops below 30. I've seen this happen a LOT at the school when we are running two different evolutions on the same hydrant line and there's a big flux in water usage. Incoming pressure drops below 30 and it warns "low supply" and "operator" for 10 seconds and if the problem is not solved it shuts down to protect itself. Personally, I think that's too high to set the low supply warning, but what do I know, I just use the things for a living.
    I may speak gibberish, but I don't talk s***! -- Dropkick Murphys

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    As I recall it was but it was a night full of trouble.15 below,water source(usual)frozen solid,fire in two areas of the home,100 gallon LP cylinders exposed,explosions in the building,limited access and then Governor issues.Just one of those deals that wasn't going to have a happy ending.But no one got hurt so it wasn't all bad. T.C.

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