I had a cat 310 pump finally fail. Luckily I had a brand new one on the shelf. I replaced the pump and while I was at it changed all the fittings, hoses, and the bypass regulator. Got it all done, primed the pump and got it going and noticed the pressure gauge read 1250 psi. I went out to the bay and pulled the gun trigger and could see an obvious increase in force so I tied the trigger in place and went and checked the pressure guage and it still read 1250ps. Turned the bay off repeated and same results so I changed out the gun and went thru it all again with the same results. Any ideas on what might be going on with this? I guess I could have a bad pressure regulator even though it is brand new .... what do you all make of this?
PSI the same when gun trigger pulled or not
- Thread starter borumrm
- Start date
Well my other bays seem to run a higher psi on the guage when the trigger is not pulled...they typically show about 1400 psi then when the trigger is pulled they show 1200. So are the pressures on the guages supposed to read the same with the trigger pulled and when it is not.
Jeff_L
Well-known member
I would assume it should read the same while pulled or not pulled. The gauge measures pressure and not volume, thus no matter the volume it will increase the pressure from the input side to the output side to your desired setting. When you pull the trigger you're just changing the volume output so the pump will maintain that same pressure.
You may see a quick decrease in pressure when you pull the trigger as your pump works to keep up.
You may see a quick decrease in pressure when you pull the trigger as your pump works to keep up.
Sounds like I might need to change a few more regulators and bypass hoses then .... Mine have worked that way for so long I guess they slowly changed over the years and I really did not notice since the pressure in the bays were all good. Thanks for the feedback.
Kevin Reilly
self serve carwashes
If you want the 1450 pressure on your pump it would seem to me that you would increase the nut on your pressure regulator. When that happens, then check it when the trigger gun is pulled and if it is less then change the tip to match the pressure that you want. All things being equal; pulley sizes, identical pumps, pressure regulator, tip size. (Of course you already know that, but just a thought!)
slash007
Well-known member
Very interesting as on all of my pumps at both washes the pressure shows about 200 psi higher when the trigger is not pulled. They all drop to about 1200 when you pull the trigger.
PaulLovesJamie
rural 5 bay SS
My pumps also read about 200 psi difference when the trigger is pulled, always have.
MEP001
Well-known member
Some regulators (particularly unloaders used with a trigger gun) don't hold the pressure as steady between the trigger pulled and not. I've always used Paraplate BR5-2 regulators, which keep the pressure within about 50 PSI.
I use a Cat 7002 pump Regulator, they are 32 years old, never done anything to them. At idle the pump pressure is 1600 psi, when you pull the handle it drops to around 1500 psi. It’s been this way as far back as I can remember.
I never really understood the difference between regulators and unloaders I guess...never really thought about it much because when I needed to replace one I just ordered what had already been on the unit. This thread got me a bit curious and I looked it up and found this link and simple explanation that clears it up for me. I am using unloaders not regulators. The link does indicate that there is more of a pressure drop with unloaders just as MEP001 notes in his post.
http://www.pumptec.com/blog/2013/04/01/unloader-vs-regulator/
http://www.pumptec.com/blog/2013/04/01/unloader-vs-regulator/
MEP001
Well-known member
Balanced pressure regulators are best for systems where the flow rate changes, like a self-serve bay with a weep gun. Unloaders are for pressure-washers with gas engines and shut-off guns - when the flow stops, the pressure on the pump is unloaded and the pump/motor can idle using much less fuel and not generating heat in the pump.
So....I'm wondering why the older Mark VII equipment uses unloaders and weep guns. Mine has been like this since the mid 80's and seems to work just fine....When the gun is released, the unloader still lets a certain amount of water out of the gun to help keep the pump from over heating as the water bypasses. Even though I read the link above, I still don't have it clear in my head what the difference is.... :-(
Kevin Reilly
self serve carwashes
Mep like you we have always used the BR5-2 and they're fine. We now have Kleen-rite's regulator which is the same as the Para-plate. When we were building equipment out here we ran wire braid from the equipment room out to the bay and I built a new system for a guy in the San Jose area and he insisted on using unloaders. I said OK (it was what he wanted) Our guys had to make at least 3 trips over there because the unloaders were blowing a hole in the hose going to the bay. I finally realized that the unloader has to spike when you release the trigger gun before it unloads to zero and the constant spike eventually blew a hole in the hose. We changed the unloaders to regulators and that solved the problem. Unloaders have their place and there are still a lot of them in the car wash business, but I would not recommend it. If you use unloaders you can't use weep guns because it will keep spiking on and off and certainly is going to create a problem somewhere in the system.
PaulLovesJamie
rural 5 bay SS
My simplistic understanding of the difference is that an unloader is designed to be a regulator with an additional capability, namely to "unload" excess pressure out a second port - eg when the trigger is released. I've assumed that the unload capability is basically like a "second regulator" that opens at a higher pressure, (ie that spike when the customer releases the trigger) hence the pressure difference we see.
No Im not an engineer, thats just how I think of it from a functionality perspective.
I have unloaders, they've worked well for 20 years. But I admit I've wondered why there is not a concensus on which to use for self serve bays and why, and whether I should be switching to regulators. I assumed theres not a concensus because I'm not the only ignorant one, many of us simply continue with what was there when we started in the wash business because it works.
No Im not an engineer, thats just how I think of it from a functionality perspective.
MEP, thats helpful, thanks.
Kevin, based on my understanding, since both regulators and unloaders have a regulating function then this spiking should be the same for both. I have to wonder if you had a bad batch of unloaders or wb hose or something. I have unloaders with weep guns and wb hose to the bays and have never experienced the problem you describe.
I have unloaders, they've worked well for 20 years. But I admit I've wondered why there is not a concensus on which to use for self serve bays and why, and whether I should be switching to regulators. I assumed theres not a concensus because I'm not the only ignorant one, many of us simply continue with what was there when we started in the wash business because it works.
MEP001
Well-known member
Paul, some unloaders work just fine in a self-serve with a trigger gun. Sometimes they work fine when they're new, then as they wear the pressure is high with the trigger released. I blasted a hole down to bone in my finger using a bay with a JE Adams unloader - with the trigger released it was climbing up to 1800 PSI. At the same wash, the owner's dad stripped a layer of skin off his forearm when he was washing the roof of his van - he was standing on the door sill holding on with one hand, and when he squeezed the trigger the pressure made him swing the tip right across his arm.
Kevin Reilly
self serve carwashes
Paul, in 1970 I bought my first self serve (4-bays and a "Follow Charlie" drive-thru) and all the equipment was Malsbary and everything was junk except the heaters. Cat was selling the 400 (today's evolution to the 430) and there was no trigger gun. When you went to wash, rinse or wax you hung on to the gun. I bought the equipment from a local Cat distributor and we put paraplate regulators on the Cat pumps, not for bypass but for safety. The wand holder had to have a catch to hold the gun in the holster because if you started the machinery and it was on high pressure you know what happens! The industry came out with trigger guns and "dump" guns. I think they still sell the dump gun. It had 2 barrels on the handle, one for pressure and when you release the trigger water just flowed out the other barrel with no pressure. At any rate I learned that the Paraplates could be used as regulators for the trigger guns. That's why I use them. We have never had a problem with them. We overhaul them when they leak, but they still handle the pressure! Also we always use weep guns because when you use shut-off guns and they are left to run and cycle within themselves they will build up heat and this will harm the pump over time. I'm not against unloaders, but if I were recommending to someone to build I would recommend regulators as opposed to unloaders because of the "simplicity" of it.
Stuart
Member
An unloader relieves the pressure from the system when the trigger is let go and is best used with positive shutoff guns. The pressure gauge will go from working pressure to basically “0” when the trigger is let go. The pump circulates the water within the system (pump and unloader) until the trigger is pulled. The load on the motor is also substantially reduced. This system should not be utilized in the winter, it is best suited for climates always above freezing.
Regulators bypass the extra pressure/water back into the pump when the trigger is let go and the system will stay under pressure. This system should always be used with weep guns as the cycling of water with-in the pump at pressure creates heat and the water temp will get extremely hot quickly. To help this heat issue the weep gun releases some water and new- less hot water is let into the pump system to keep from overheating. The pressure could bump up zero to 100#, however if the pressure goes up much more- the pressure regulator needs replaced or rebuilt. This extra pressure usually is due to the springs/washers inside rusting up and will not move. Using an unloader or pressure regulator can be used on electric motor or engine powered systems.
Regulators bypass the extra pressure/water back into the pump when the trigger is let go and the system will stay under pressure. This system should always be used with weep guns as the cycling of water with-in the pump at pressure creates heat and the water temp will get extremely hot quickly. To help this heat issue the weep gun releases some water and new- less hot water is let into the pump system to keep from overheating. The pressure could bump up zero to 100#, however if the pressure goes up much more- the pressure regulator needs replaced or rebuilt. This extra pressure usually is due to the springs/washers inside rusting up and will not move. Using an unloader or pressure regulator can be used on electric motor or engine powered systems.
