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switching from 3/8" to 1/4" hp supply hose

Eric H

Eric H

Well-known member
The bays at my wash use 3/8" hose to run from the pumps to the top of the booms and are due for replacement. I am thinking about running 1/4" as a replacement to reduce chemical time changover. Has anyone done this or have a similar setup? Are there any issues?
i have looked up the flow charts and pressure loss charts and found that: running 3.2 gpm (2506 tips) a 1/4" hose will have a pressure drop of about 300psi for the approximate 80' run to the furthest bay (3 gpm drops 400psi at 100' of hose according to chart). That means that the pump for that bay needs to be increased from 1200psi to approx 1500psi. If I stick with the 3/8" hose the pressure loss is slightly less than 50psi.
Is it worth it to switch to 1/4" to reduce changover times?
 
Run 3/8 stainless tube. Its almost the same cost and should last a lot longer than hose. Im glad I switched several years ago
 
I wouldn't do it. I decreased the size on the bay that shared the eq. room wall. The whole run all the way back to the pump was less than 25'. There was a noticeable difference in the pressure, enough that a customer or two commented. If you go cranking up the pressure to compensate you will draw more amps, possibly tripping pump motor overloads as well.
 
There's more to it than trying to make up the 300 PSI lost by line friction. I tried the same thing at a customer's request, and it wasn't just a matter of turning the pump up 300 PSI, I had to crank it up to 1800 to get 1100 in the bay, and that was maxing the 3 HP motor. The changeover time wasn't affected as much as you might think - it went from about 18 seconds to about 14 seconds.

I've been thinking about ways to reduce the changeover time in the farthest two bays, which are also about 100 feet down. One thought was an injector at or near the boom and separate tubing for soap and wax run to the injector. I went so far as to try a couple injectors right on the outlet of the pump, but I was disappointed in the massive loss of pressure it took for it to draw. Another idea was to run three separate high-pressure lines to the boom with each line having a solenoid and always staying full of soap, wax or clear water, but obviously that would cost too much.
 
Boywonder, Can you tell us more about the Stainless tubing? Did you run 1/4" or 3/8"? Where is the best place to buy?

MEP, Thank you. I have 5hp motors but at 1800psi I worry about having issues with other components in the system. IIRC, brass fittings are only rated to 1200psi, so we are already at max pressure. I actually set my bays to 1200 psi at the gun so some of my pumps are already close to 1500psi.
 
I originally ran 1/4" stainless tubing to my bays, then switched out to 3/8" stainless tubing. Made a big difference in the draw on the motors and more pressure and volume at the bay gun. I would go with the 3/8" stainless, if fact, I have done all my installs with 3/8" stainless. I get it from PAC Stainless, use compression fittings. As they say..."set it and forget it"
 
I'm redesigning my roof trough and am contemplating doing everything in stainless tubing of one gauge or another. 1/4" for low pressure functions and 3/8" for the high pressure runs. I will have this place for another 20 years at least and would rather spend a little more now and make my life a little less hectic. If I get it set up the way I want to, I should only have to worry about the check valves.

On a different note, I changed my bay hose over from 3/8" to 1/4" and love how easy it is to use. I will probably change my whip hose and boom hose over as well.
 
I got my 3/8 stainless through my chemical distirbutor who got it from a food plant supply place a couple hours away its 316ss. You need to watch the grade of stainless. The auto distributor install 304 and wasn't paying attention to the seams of the tube and developed leaks in the seam do to stretching of the seam. But in that case I think the tool was smarter than the operator. I wouldn't go the the expense of running stainless tube for low pressure, I think its a waste of time and money. You could also think about changing tips, that 2506 tip you mentioned seems awfully big.
 
2506 tips at 1000-1200 PSI is pretty standard. I would never go smaller unless for some reason there was a need for much higher pressure.
 
For stainless steel tubing and compression fittings, try:

MRC Global
47 South Maple Street
Bellingham, MA 02019
508-966-3205

The best hp bay supply system...ever! Tubing is inexpensive and easy to work with if you use the right tools. Fitting are expensive but never have to be replaced. Properly designed and installed, the cost is only 10 to 15% higher than 100R1 hose with none of the disadvantages.
 
Windtrax sells stainless tubing and fittings. Also on the high pressure even if 1/4 inch will handle the flow the velocity is much higher and the 1/4" hose will jerk a lot more and with the higher pressure I would think won't last as long.
 
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MEP001 said:
Another idea was to run three separate high-pressure lines to the boom with each line having a solenoid and always staying full of soap, wax or clear water, but obviously that would cost too much.
Click to expand...
My high pressure changeovers are 4.5 sec for 2 bays, 6 sec for 2 bays, 9 sec for the furthest bay (approx 70' of 3/8 hose total). I'm not happy with that, I've wondered several times how to reduce my changeovers... with an 18 sec changeover I might be thinking that 3 separate lines is cheap.
 
PaulLovesJamie said:
My high pressure changeovers are 4.5 sec for 2 bays, 6 sec for 2 bays, 9 sec for the furthest bay (approx 70' of 3/8 hose total). I'm not happy with that, I've wondered several times how to reduce my changeovers... with an 18 sec changeover I might be thinking that 3 separate lines is cheap.
Click to expand...
I agree - I'm running a bigger tip and higher pressure in the farthest two bays to keep changeover down to about 14 seconds, but I'm sure over the last ten years it's cost more in water and chemicals than it would have cost in hose and solenoids.

Do you happen to know of an injector that won't cost more than about 10% of the pressure to draw properly? I still want to try my idea.
 
MEP001 said:
Do you happen to know of an injector that won't cost more than about 10% of the pressure to draw properly? I still want to try my idea.
Click to expand...
Sadly, no I dont. I usually count on you guys for that kind of info.
I worry about customer perception and satisfaction more than the extra water/soap cost. Thats actually one of the features of the etowah valley timers that I really like, you can pause the timer for a specified # of seconds for each function so you could pause for 14 seconds to compensate for the changeover time.
 
I like that idea. After all these years, customers understand the long changeover, and no one's ever complained. For the most part, the only ones who use the farthest bay are there to wash for a long time, and those extra seconds don't really matter to them. I'd still like to fix it.
 
Etowah
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