Dump Gun Options & Engine

810f250

810f250

Griffs Services PowerWash
Looking for the best suitable dump gun for use with (8 gpm @ 3600 psi) rated @ over 210F, would like it to be 48" long on the high pressure side.

I have see couple from Cat pumps and one from General pump but they are rated for 140F, and a also style from safety jet,

what others are available

Please post,send me info or a link and your pricing.

Also looking for pricing on a 38 hp Kohler engine with flat top air filter and 1 1/8" shat diameter. Delivered to 21043
I taught I saw 1 1/8" shaft 38 hp's but if I am wrong does it have a 1 7/16" sheave to fit my existing pulley on my 30HP Kohler.

Thank You.
 
Last edited:
Russ,

For all of the positives of using a dump gun I keep coming back to the one glaring negative. The flow of water never stops while the machine is running! This increases the amount of water that must be controled and recovered. In some areas this isn't an issue but in many areas it will come into play. Years ago contractors were building their own dump guns using high pressure ball valves hydraulic fittings and an open gun.

My 2 Cents.
 
Russ Spence said:
I deleted the post just before you posted Nigel, I saw that you had found the same gun for less money already.

I dont use them although I felt they may be a good idea especially in the colder climates. Whats your take? Sell me on your idea!
Click to expand...

I saw that Russ ,no problem!

My idea Russ is to reduce/remove the pressure spike associated with my trapped pressure unloader , I feel that it will shorten the life of any system, and more so on mine as my spike is 4300psi it is well over 10% of the system maximum operating pressure of 3600 psi.

Larry Hinckley said:
Russ,

For all of the positives of using a dump gun I keep coming back to the one glaring negative. The flow of water never stops while the machine is running! This increases the amount of water that must be controled and recovered. In some areas this isn't an issue but in many areas it will come into play. Years ago contractors were building their own dump guns using high pressure ball valves hydraulic fittings and an open gun.

My 2 Cents.
Click to expand...

Good point Larry, I am putting a ball valve up stream the gun so when the trigger on the gun is released the gun dumps the water but for any extended period I would close the ball valve. I hope to reduce the number of times I expose the pump to the killer pressure spikes.

I really need a higher pressure rated pump, at the same flow 8 plus gpm, but bigger than the TSF2021 the prices for pumps are 5 times more expensive about $3500 to $4500.

I would like, really like a General Pump KE series pump or better yet the monster HF series. (((( Santa are you listening ))))
 
Nigel, your getting too complicated for me. Are you a mathematician by chance. LOL :banghead:

It is very interesting reading your posts as you have a great understanding of formulas and calculations pertaining to our world in Pressure Cleaning.
 
Chris Tharpe said:
Nigel, your getting too complicated for me. Are you a mathematician by chance. LOL :banghead:

It is very interesting reading your posts as you have a great understanding of formulas and calculations pertaining to our world in Pressure Cleaning.
Click to expand...

Hey Chris, I had no math in the above post, lol , all the numbers were taken off the guage.

Just looking for a solution to reduce or eliminate spike pressure, looks like I might be leaning towards a flow type unloader, wish they had a compensating unloader rated at least 4000 psi 8 gpm. I just dont like how everything sounds, when I release the trigger at 8 gpm 3600 psi, sound like some thing would blow.

Anyone knows at what pressure a safety relief valve opens when it comes direct from general pump?
 
catch 22

After reviewing over and over my spike pressure problems I have determined it is catch 22, and wanted to share understandings

I am of the belief that I cannot run my pump (TSF2021) at the max rated 3600 psi continuously in combination with the my current trapped pressure unloader, it would seem that the pressure spike is caused by the internal valve sizing, design of the unloader and the nature of springs.

Refer/print this unloader schematic here to assist in understanding.


The pressure and volume of water needed in the void above the piston has to overcome the spring tension , O ring friction and the force created by the incoming flowing water pressure on the underside side of the unloader piston.


It is a balancing act, the manufacture instructions are to allowing at least 5% of the pumped volume to bypass to the tank.


(lets just say for ease of explanation, that if bypass port is 5% open when then 5% of the water volume is bypassed to the tank), this is like having the unloader piston in the "get set" position so that the force required to move the piston the remaining 95% open is far less than to have it move from rest (or the full 100% which is zero bypass flow position).

So what happens when I release the trigger, the water continues to be pumped (unloader check valve is still open, hose volume may increase because the hose swells), the pressure builds until the (downward) force created on the piston surface area (top side) is enough to overcome:

1)the piston frictional forces (upward)
2)the (upward) force created on the surface area of the underside of the piston.
3)The spring force (upward) (another disadvantage, the stiffer the unloader spring the higher the spring "k" coefficient ) it would require more downward force to compress it to achieve a small unloader piston movement)


Then the check valve closes and the bypass port opens.



Therefore an unloaders internal valve sizing (the piston surface area upon which the downward force acts) has to be matched to the pumps flow and pressure output (#2), criteria #1 & #3, this is critical in minimizing the pressure spike, so having a "one size fits all" unloader would not be my best choice.
 
Great Info
810f250 said:
After reviewing over and over my spike pressure problems I have determined it is catch 22, and wanted to share understandings

I am of the belief that I cannot run my pump (TSF2021) at the max rated 3600 psi continuously in combination with the my current trapped pressure unloader, it would seem that the pressure spike is caused by the internal valve sizing, design of the unloader and the nature of springs.

Refer/print this unloader schematic here to assist in understanding.


The pressure and volume of water needed in the void above the piston has to overcome the spring tension , O ring friction and the force created by the incoming flowing water pressure on the underside side of the unloader piston.


It is a balancing act, the manufacture instructions are to allowing at least 5% of the pumped volume to bypass to the tank.


(lets just say for ease of explanation, that if bypass port is 5% open when then 5% of the water volume is bypassed to the tank), this is like having the unloader piston in the "get set" position so that the force required to move the piston the remaining 95% open is far less than to have it move from rest (or the full 100% which is zero bypass flow position).

So what happens when I release the trigger, the water continues to be pumped (unloader check valve is still open, hose volume may increase because the hose swells), the pressure builds until the (downward) force created on the piston surface area (top side) is enough to overcome:

1)the piston frictional forces (upward)
2)the (upward) force created on the surface area of the underside of the piston.
3)The spring force (upward) (another disadvantage, the stiffer the unloader spring the higher the spring "k" coefficient ) it would require more downward force to compress it to achieve a small unloader piston movement)


Then the check valve closes and the bypass port opens.



Therefore an unloaders internal valve sizing (the piston surface area upon which the downward force acts) has to be matched to the pumps flow and pressure output (#2), criteria #1 & #3, this is critical in minimizing the pressure spike, so having a "one size fits all" unloader would not be my best choice.
Click to expand...
 
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