Pressure tank size

Users who are viewing this thread

NathanJ

New Member
Messages
2
Reaction score
0
Points
0
Location
Northern Virginia
I have an Amtrol PF32 pressure tank that is supposed to have a 9.4 gallon drawdown at 40/60. My problem is that I am only getting 6-7 gallons out of it before the pump kicks on.

My pump flows 10 GPM and I have even temporarily upped the pressure so it is 40-65psi. My pump is able to fill the tank in 39 seconds with these settings.

I have drained my tank and increased the pressure to 38PSI from 28 PSI ( the switch was set to 30-50). When drained, the tank feels light like all the water has been removed.

How come I am getting 3 gallons too little out of this tank?

Thanks,
Nathan Jones
 

NathanJ

New Member
Messages
2
Reaction score
0
Points
0
Location
Northern Virginia
Thanks for the replies guys. I only raised the cutoff pressure, which allows the tank to fill with more water. The 10 GPM was actually calculated by taking the volume of the drawdown and the time it took to repressurize the tank. It was nearly exactly 10GPM.

The pressure tank was installed in Nov 2004, so it isn't new, however it didn't feel like there was any water in it after I drained it. I was able to rock it side to side easily.

I'm thinking about getting a larger pressure tank, but before I do that I would like to understand what is happening to mine. The only thing I know to check is the bladder pressure with another gauge. But I believe mine to be pretty accurate.
 

Valveman

Cary Austin
Staff member
Messages
14,599
Reaction score
1,296
Points
113
Location
Lubbock, Texas
Website
cyclestopvalves.com
You could still have three gallons on top of the bladder, and it would still feel light. Bladders are busted from the pump cycling on and off. The diaphragm breaks like bending a wire back and forth. A tank sized for a one minute cycle is required, two minutes is better, and no cycling is even better. A CSV to stop the cycling will work with as small as a 4.4 gallon tank like pictured on the left. You can see how it works at this link. www.cyclestopvalves.com
 

Valveman

Cary Austin
Staff member
Messages
14,599
Reaction score
1,296
Points
113
Location
Lubbock, Texas
Website
cyclestopvalves.com
A 32 gallon tank has 20.27 gallons of draw down at 20/80. That is stretching the heck out of the bladder though. Many of these tanks have a metal dome above the diaphragm, so they only stretch so much, no matter how high the pressure goes. You can play with different pressure settings and see the draw down using the calculator at this link.

http://www.cyclestopvalves.com/runtime_app.php
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks