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  • #16
    I am FINALLY used to working with Dacron Hose instead of Leather, and now this discussion starts up............
    Well...governing engine speed means more than just pulling back on the reins these days.
    Member IACOJ

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    • #17
      I was just asking this question.....

      We have a pumper/tanker with the RPM and Pressure pump settings, and I not being the engineer, asked what the difference was between this and the Pressure/Volume setting on other apparatus. I was told it was the same as the Pressure/Volume settings for the 2 stages of the pump.

      "But Captain, it's a single stage pump......" ( Blank stare as he reads the pump plate that says "Single" in the stage slot.

      We have no literature on this pump, even though it is only a couple of years old, and the manufacure has been slow in getting it after my request. ( I run the maintenance program, I want details on what I'm putting a wrench to )

      Thanks for the clarification folks. It makes sense now that it has been explained.
      We do not rise to the occasion. We fall back to our level of training.

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      • #18
        You're welcome, glad to help clear things up. It's a common misconception that it has something to do with the pressure/volume settings of a 2 stage pump, but as you can see it's something completely different!

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        • #19
          I have heard from a few people say with the class 1 governor's that if you are drafting water you should use the RPM mode, is this true? or has anyone else heard this?

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          • #20
            Dacron hose, not leather? What is next, getting rid of rotary and piston pumps?

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            • #21
              From the Class One Manual

              For every new delivery I do I take the basics from the Class One Manual and put it into a hand out for all the members of the department. What I have pasted here is just the basics and highlights I put in the handouts. Also there is a lot if info on the Class One website and CD's they hand out at shows. They have instructional vidios you can play on your computer, downloadable from their site.


              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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              • #22
                Regarding using RPM mode for drafting, Yes do do have to start a draft operation in the RPM mode. The reason for this is that you have to show pressure on the pump of at least 30 pounds before the govener will let you increase the pressure while in the pressure mode. If you have no water in the pump you cant have the 30 pounds pressure needed so will not be able to increase the throttle. Set the controller to RPM, pull your prime, show pressure on the gauges, then switch mode to "pressure'.

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                • #23
                  Sometimes I hate these new fangled gadgets. But then I never thought those internal combustion engines would replace our horses and steamers.
                  Vintage Firefighter: The older I get, the braver I was.

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                  • #24
                    hmmmmm

                    All you guys replaced your horses, steamers and piston pumps............
                    Hmm guess im a l'il behind the times.........

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                    • #25
                      easy way is this:
                      thinking of it like banging some chic (fat chic in my case)
                      rpm or revolutions per minute is how many times you hump her in one minute
                      psi is the pressure, or force, you use.
                      so do you want to hump her 40 times, aka 40 rpm, or try and break her pelvis, aka lots of pressure

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                      • #26
                        Last year our dept. took delivery of a new pumper that has an rpm/pressure governor. Our problem is when we are in pressure mode and running off of the tank of the engine, when we open the hydrant and switch from tank to hydrant we get a spike in pressure of about 230lbs for about 3 or 4 seconds with the governor set at approx. 130 lbs. The pump and the governor manufacture say that there is nothing we can do about it. They tell us that the governor can not compensate for the momentary pressure increase when we open the hydrant.It is a waterous pump and i think it is a class III governor? Wondering if anyone else has had that problem.

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                        • #27
                          You could switch to RPM mode when you open the hydrant and bring the RPMs down coordinated with the opening of the hydrant, but you'll still get either a pressure loss or increase, depending or fast/slow you are.

                          Edit-Just thought of another way, you could set your relief valve at your current pressure and you'll just dump out the pressure during the switch.
                          Last edited by edge1317; 10-21-2007, 03:40 AM.

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                          • #28
                            Originally posted by jercvfd View Post
                            Last year our dept. took delivery of a new pumper that has an rpm/pressure governor. Our problem is when we are in pressure mode and running off of the tank of the engine, when we open the hydrant and switch from tank to hydrant we get a spike in pressure of about 230lbs for about 3 or 4 seconds with the governor set at approx. 130 lbs. The pump and the governor manufacture say that there is nothing we can do about it. They tell us that the governor can not compensate for the momentary pressure increase when we open the hydrant.It is a waterous pump and i think it is a class III governor? Wondering if anyone else has had that problem.
                            Try opening the valve for hydrant water in sloooooooowly
                            Nobody ever called the fire department for doing something smart.

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                            • #29
                              We have tried reducing pressure beforing taking hydrant water but no considerable difference. The only way we have been able to switch from the tank to a hydrant without getting the spike is to idle the truck and then switch over. Problem is u can not do that with guys in a structure. I think maybe part of the problem is the intake and the tank to pump are electric, there is no opening them slow , but thanks for the advice

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                              • #30
                                No what haweater was saying when your hydrant man connects you to the hydrant and opens the hydrant ITSELF. That if he opens it very slowly that the pump won't have such a surge and will have less pressure to readjust itself over time.

                                Also, did you try the relief valve?

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