Newbie Questions: Regulator/Unloader and Check Valves

[Matt]

First off, thank you all so much for taking the time to bring your expertise to this BB. I have one year under my belt at my 2 bay SS and this board has helped me immensely in learning the business!

My first question is this: What is the purpose of regulators, unloaders, and bypass regulators? To be a little more specific, I have a Mark VII pump station with Cat 5CP2120 pumps. The pump discharge is plumbed to (what I assume) is a J E Adams regulator/unloader. It has the pressure gauge on top, an accumulator on the bottom and the bypass feeds over to to the pump suction line. Discharge feeds out to the bays. I had to replace one of these and apparently installed an incorrect size as the pressure would max out and drop to zero when the trigger was not being pulled in the bay - it shook the whole pump stand when this was happening. Called and talked to tech at WT, ordered a bypass regulator (BRM5-2) installed it and everything seems to be okay since then. So now my other regulator is going bad. I can't seem to figure out why the original configuration didn't need a bypass regulator and now it does. Is there a better way to configure this?

Next problem: I have low pressure tire cleaner coming back through the lines, through the pump and into the hot water reservoir tank. The problem just started occurring. In reviewing old threads I have read that it could be a faulty check valve - my problem is, I don't see a check valve anywhere around the pump stand. If, in fact, it does not have a CV why would I have this problem now, and not all the time? Where is the recommended place to place a CV to prevent the backfill and what style do you have success with?

Again, thanks for helping out and I look forward to contributing to the board!

Matt

 

[Earl Weiss]

Usualy several lines meet at a manifold above the bay. That is how you only have one hose in the bay yet different products come thru it. Sonds like one of the lines in yours might be air for an air assist on some low pressure products. Is the product coming back thru the air line.? Whatever line it's coming bck thru would be the one with the bad check valve.

 

[Matt]

I've replaced all of the check valves at the manifold and double checked them. I believe my product is coming back through the HP line, back through the HP pump, and then back into the holding tank. Does anyone have a CV at or around the HP pump station? or what about before the manifold above the bay?

 

[MEP001]

I had to replace one of these and apparently installed an incorrect size as the pressure would max out and drop to zero when the trigger was not being pulled in the bay - it shook the whole pump stand when this was happening.

Either you replaced a bypass regulator with an unloader, or it had an unloader that had been modified. An "unloader" is designed for use with a shut-off gun so when flow stops the pressure on the pump drops to zero. A bypass regulator is what should be used with a weep gun. In my opinion, you did yourself a favor by changing to the regulator you used. They keep the pressure more steady and last many years.

I have low pressure tire cleaner coming back through the lines, through the pump and into the hot water reservoir tank.

You may have two problems here. First, the pump should prevent a reverse flow of water from the bay to the reservoir. If tire cleaner is backing up, it could be bad pump valves/o-rings, bad high-pressure seals or a bad regulating unloader. Second, there is usually (but not always) a check valve with a low cracking pressure (very easy to blow through) on the line between the reservoir and the pump. Many systems use hot water from the reservoir for soap and wax, and city pressure for rinse supplied with a solenoid. Without a check valve the cold water would overfill the reservoir. If there isn't a check valve, I wouldn't recommend adding one - find the cause of the problem instead.

 

[phred113]

First off, thank you all so much for taking the time to bring your expertise to this BB. I have one year under my belt at my 2 bay SS and this board has helped me immensely in learning the business!

My first question is this: What is the purpose of regulators, unloaders, and bypass regulators? To be a little more specific, I have a Mark VII pump station with Cat 5CP2120 pumps. The pump discharge is plumbed to (what I assume) is a J E Adams regulator/unloader. It has the pressure gauge on top, an accumulator on the bottom and the bypass feeds over to to the pump suction line. Discharge feeds out to the bays. I had to replace one of these and apparently installed an incorrect size as the pressure would max out and drop to zero when the trigger was not being pulled in the bay - it shook the whole pump stand when this was happening. Called and talked to tech at WT, ordered a bypass regulator (BRM5-2) installed it and everything seems to be okay since then. So now my other regulator is going bad. I can't seem to figure out why the original configuration didn't need a bypass regulator and now it does. Is there a better way to configure this?


Matt

Matt:

The Unloader you installed did not have the check valve removed. When you remove the check valve (from a trapped pressure type - most common) it becomes a (complex) regulator. There are advantages to this depending on your valve and options.

A regulator will maintain a constant pressure and limit max pressure, but it does this at the cost of extra energy and wear to the pump and system.

The advantage of a neutered unloader is that it can have a larger bypass seat and therefore decrease the amount of air bubbles that are sent back into the pump - that cause cavitation erorsion, noise, and can eventually break valve discs.

Your trapped pressure unloader may have killed your check valve and caused you soap problem, too.

 

[Matt]

Thanks all for replying. I ordered a (correctly sized) regulating unloader and a bypass regulator so hopefully that will solve my problems.

I am still confused about one thing though - from my holding tank to the tip of the gun, there is nothing preventing backflow from the low pressure lines into the main supply except for the pump and regulating unloader. Do regulating unloaders only allow flow one way, thus acting as a check valve for the system? If that regulating unloader fails (as mine presumably did) will that low pressure backflow kill my pump?

 

[MEP001]

Do regulating unloaders only allow flow one way, thus acting as a check valve for the system?

It should if it's all in good condition. A bad o-ring or a worn seat or poppet or debris caught between them will allow the reverse flow.

...will that low pressure backflow kill my pump?

No, but it wastes tire cleaner and it will **** off your customers. If you have aerated tire cleaner and the air makes the pump lose prime and it can't recover on its own, that will cause premature failure of the seals.

 

[MEP001]

A regulator will maintain a constant pressure and limit max pressure, but it does this at the cost of extra energy and wear to the pump and system.

Not a bypass regulator that's functioning properly. It should maintain the set pressure within 5% when the flow changes. It's increased pressure on the system that causes more wear and energy consumption, and when the pressure is constant so is the rest.

 

[jcedwards]

Not a bypass regulator that's functioning properly. It should maintain the set pressure within 5% when the flow changes. It's increased pressure on the system that causes more wear and energy consumption, and when the pressure is constant so is the rest.

I think this guy was comparing the no load state of a properly functioning unloader running in bypass versus the constant load state of a regulator. If so, he is correct.