# Thread: Different pressures at the pump

1. ## Different pressures at the pump

Ok, I thought this was a No-brainer until we were having this discussion today. Here's the scenario. Specific pressures are not important for this disscussion.

We'll make this simple. You have three different lines running, different lengths and/or different diameters with different nozzles. And each one doesn't take or need the same pressure to operate efficiently.

How do you deal with the differing pressures needed at the pump panel?

2. run the pump at the highest pressure and gate down the other lines.

If you are operating a 150 psi line and need to charge another line to 200. Open the new lines gate all the way, gradually throttle up to 200. While doing that gate down the original line to keep it at 150.

If you have the 200 psi line operating and need to open something at 150 its pretty easy. Just gradually open the gate for the 150 line and stop when it gets to 150 psi, just make sure your 200 psi line doesnt lose any pressure.

3. OK, that was what I have always been taught. Run pump pressure at the highest needed and gate everything else down.

Two new thought processes were given me today.

1). you don't want to gate down the other lines because it will diminish the GPM.
2). it will add more force and pressure to the valve that is partially closed.

I know what my thoughts are on this. What are your thoughts?

4. Originally Posted by RJAbbott
OK, that was what I have always been taught. Run pump pressure at the highest needed and gate everything else down.

Two new thought processes were given me today.

1). you don't want to gate down the other lines because it will diminish the GPM.
2). it will add more force and pressure to the valve that is partially closed.

I know what my thoughts are on this. What are your thoughts?
1). If you didn't gate down line at the you would get the GPM that that the full pump pressure would push through the line. The purpose of gating down is to bring the pressure, and consequently the flow down to what's desired. Remember, what we're trying to accomplish is GPM flow. Pressure is how we achieve that flow for any given line.

2). So what? They are designed to take 600 psi plus safety factor. One caution - Always lock the valve in the gated postion if they have a locking mechanism (usually by turning the pull handle, Hale B and BL valves, turn the knob on the lever). Waterous valves and others will pull themselves shut if you don't.

Stay safe out there, everyone goes home!

5. Originally Posted by RJAbbott
Two new thought processes were given me today.

1). you don't want to gate down the other lines because it will diminish the GPM.
2). it will add more force and pressure to the valve that is partially closed.

I know what my thoughts are on this. What are your thoughts?
My thoughts....Tell whomever gave you these two thoughts to go back to basic pump school.

6. ^^^^ What he said. If only opening it half way was bad, the valves would be on-off switches.

7. Bells and whistles and electronic gadgets have been added to pump panels to make it easier for the engineer, but basic pump hydraulics are the same as they have been for decades. Gate the valve down on the line that you want to have less pressure.

By the way RJ, you didn't explain how the other person would manage different pressures on multiple lines. Did he give you any insight? Maybe we all can learn something new?

8. Thanks everyone, what I am hearing here is what I have been taught my entire career. I just wanted to verify that I was not the one who was off-base and that there was some new philosophies that I was not aware of.

Thanks again everyone. We can probably let this thread die because as I said in the beginning I have always thought this was a no-brainer.

9. Unfortunately, people with no brains don't understand concepts that are no-brainers. It is kind of a play on words if you think about it.

10. somehow I hit the button twice... Sorry

11. Originally Posted by nmfire
Unfortunately, people with no brains don't understand concepts that are no-brainers. It is kind of a play on words if you think about it.
You must know my CHIEF

12. Thanks again everyone, Thanks nmfire for the email.

Here's where all this stems from. I have been on vol depts. and was on a private paid department. I was a Driver/Operator/Engineer whatever you want to call it in my last paid dept. I recently had to leave my paid dept and I took another job in another dept. A lateral transfer was not an option. So I am one of about 12 rookies/recruits with literally a handful of senior officers. So they are constantly inundated with retarded questions. So when a question is asked, like "why are you not gating that valve down so those guys on that line aren't getting their a**es kicked" the standard answer is "That's not how we do it here".

Now, I have to walk a fine line between being a rooky and "put up and shut" and making suggestions in a way that the officers think it's their idea.

It's frustrating to say the least.

13. Originally Posted by FWDbuff
My thoughts....Tell whomever gave you these two thoughts to go back to basic pump school.
What he said.

14. ## Aerial-Tower Nozzles

Our new tower truck has only one nozzle, as opposed to the two that the old truck had.

Question:
It is probably likely that the new tower's nozzle can handle double the flow of the older two? The older truck had a GPM max capacity of 3,000 GPM.

15. ## One step farther -

I suggest that you set up the main pump pressure at least 10 psi above the line with the highest pressure requirement and then gate every valve back to the desired discharge when that line is flowing. Now when these lines are shut off the individual discharge gauge will read the same as the master discharge gauge on the pump. When the nozzle is opened, the individual discharge gauge will drop to the correct pressure. In this way the pump operator can monitor each individual line and know when that line is taking water. You might just be able to save somebody's A** if the fire conditions are getting worse and the line isn't flowing.

16. BFDFREQ

If well a tower can have a pair of master stream @ 2.000 gpm each one, it didn't automatically means you coul flow 4.000 gpm trough those.

The real culprit it's FL, yes, the telescoping waterway it's not capable of flow 4.000 or 3.000 gpm with acceptable FL, so a realistic max flow will be some of 1.500 gpm's.

Regards

17. ## Wow!!

You mean after over 30+ years as a Firefighter/Engineer I now learn that it is BAD to gate down on an outlet when a lower pressure is needed. I bet there are some out there who also use their relief valve as a safety ??

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