PSI test

[vincent]

Was concerned about the pressure drop at the gauge when using either my greenhorn (jetted at 02 straight across) and the 360i.

this video shows just using the 360i. I have 125 of of solution hose out. I set the psi at 400 to get a good starting point.

As you notice, it drops 200 psi when the trigger is pulled, but it also maintains that dropped pressure. I did the same with the greenhorn and the same thing happened.

After this video was taken, I talked with Les, and made sure the belt was tight on the waterpump. And I also took the filter off inside of the waterbox.

Any other thoughts or has anyone experienced this.

6]http://www.youtube.com/watch?v=eQ6zELjmNB06]

 

[Giorgio]

I forget how much my PSI drops when the trigger is keyed...

I'll check tomorrow.

A 200 psi pressure drop doesn't sound too alarming if your running high flow.

It could be a volume problem?

A bucket test wouldn't hurt.

You don't run a fresh water tank do you? Once I experienced huge pressure/volume drops. Turns out a gallon of stripper broke and spilled into the fresh water tank causing the pump to cavitate.

Also, when was the last time you de-scaled and cleaned your screens/filters?

 

[vincent]

I forget how much my PSI drops when the trigger is keyed...

I'll check tomorrow.

A 200 psi pressure drop doesn't sound too alarming if your running high flow.

It could be a volume problem?

A bucket test wouldn't hurt.

You don't run a fresh water tank do you? Once I experienced huge pressure/volume drops. Turns out a gallon of stripper broke and spilled into the fresh water tank causing the pump to cavitate.

Also, when was the last time you de-scaled and cleaned your screens/filters?

I do run a fresh water tank, pump keeps the waterbox filled just fine.

The machine was put in service the 2nd week of August of this year. Plus I run soft water.

 

[Lee Stockwell]

Could be trash or other blockage in a hose or fitting. The pressure gauge won't show this unless water is FLOWING, as you demonstrated.

To get a starting baseline free-flow gpm number for the pump hook a very short open hose to the machine front and measure how much water you pump every 60 seconds into a 5 gallon bucket. Do this at maximum pressure and at your 400 psi set point.

I have four 100' reels of solution hose on my truck. I likewise bucket test each of these in the same manner. Sometimes a bad quick coupler or internally herniated hose will cause a measurable blockage.

If the machine plumbing and hose assemblies check out, then move on to the various tools to verify their flow at working pressures.

Good job on posting the Youtube Vince.

 

[Bob Foster]

Got basically the same setup Vince. Same pump. That's normal because its a CAT 3CP3 GPM pump. So all you do is set it higher so when it flows its at pressure you want to maintain it at. No sudden blast when you trigger so its no big deal.


If you hold the trigger on and you see it keep dropping instead of dropping to a certain point and staying at that pressure then you would have a problem (that would be some form of filter blockage)

New Judsons come with a 4.5 GPM pump and it doesn't drop as much on trigger.

 

[joe harper]

Vincent,

On a standard flow wand.."It is NOT uncommon to have a 50 psi drop....."

If you are running 12 flow...HIGH FLOW...it is NOT uncommon to see a 100 to 200 psi drop...

You are running a 3 cp Cat pump... :idea:

IT is normal...!

The pump is STEADY.....no cavation...!

TRY CRANKING THE RPM's up a "100 rpm"...should be FINE... !gotcha!

 

[Duane Oxley]

If you measured PSI at the wand, you'd get a "real" reading. And you'd find that the actual drop is even more than the machine shows.

Basically, there are 2 things at work if the system is functioning properly:

1.) A 1/4" hose offers substantial resistance to flow rates used in carpet cleaning. And that resistance results in a pressure drop. If you went to a 3/8" hose (which few people do, because it's too heavy / bulky, etc.), you'd see about 50 PSI drop in pressure.

2.) The jet size in relation to what the pump can deliver. If the jet size allows less than the pump can deliver, the drop will be less. If it allows more than the pump can deliver, the drop will be more. This is because the pump always pumps the same rate and amount, regardless of whether it's going to your wand, or bypassed elsewhere. And a specific rate through a smaller jet results in more pressure, while the same rate through a larger one results in lower pressure.

If it's NOT functioning properly:

It's true that you could have a regulator issue. This is especially more likely if the system has some age on it. So, if this drop in pressure is more than what you're used to with the same system, you might look there.

As Les told you, there may be some restriction on the inlet in the water box, so removing the filter makes sense. However, if it made no difference, reinstall it. It's there to prevent debris from getting to the pump and getting stuck in a check valve, or passing through and plugging the regulator hose, etc.

Personally, I'd look in the pump first. It's likely that you have a burned cup (if it's a Cat 290) or a check valve with trash in it (more likely in a 3CP, 5CP, etc.). If you have a burned cup or trash in a check valve, in essence you'll be running with only 2, etc. pistons or plungers operating correctly, which means that your pump will be flowing 2/3 as much as it was designed to do, resulting in a big pressure drop.

NOTE: If your pump is running on 2 pistons or plungers out of 3, then there should be a noticeable vibration in your pressure hose. However, sometimes all 3 are damaged, but still have enough material to pump to some extent. If that's the case, flow will be reduced, but vibration will be less evident.

Good luck.

 

[ACE]

I had a similar issue on my Steamway. I turns out a high temp bypass valve was leaking water.

 

[Larry Cobb]

Vincent;

I agree with Dwane.

Check the gallons delivered in one minute to determine what is flowing.

Check the pressure at the wand WHILE spraying.

Larry

 

[Loren Egland]

Though I don't understand such things, I seemed to have read that some machines have an unloader valve that usually drops this much psi when the trigger is keyed, but a pressure regulator like on my Powermatic will usually only drop about 25 psi.

I often wonder about this difference when I read the psi numbers people are using when discussing flow through total jet openings, such as 10 flow, 12 flow, 15 flow, etc. The actual water flow could be much different on different machines as a result. 10 flow might actually be the same as 15 flow if there is a greater pressure drop at 15 flow.

Or am I all wet?

 

[ACE]

Most of the machines I have used with an unloader valve do not show any reading until the wand is keyed. It may have a small leak somewhere that is causing it to show a reading.

I always measure PSI as what the gage shows at the machine when the wand is keyed. Hooking up a PSI gage ATW as Larry suggest will only show a huge loss in pressure due to the hose run, although the static pressure will be the same until keyed.