Single hose VFD systems, suggestions ?

[softsuds]

Going to remodel my ss wash and I really like the idea of the VFD systems with the single hose to the bay and no more low preassure pumps. Does anyone have experience they would share both with any pros and cons about their system or recomendations of a system?

Thanks

 

[thoffmanjr]

http://www.autocareforum.com/Articles/howto/tom-hoffman.html

We’ve done our own locations and have built it for three different friends at 11 location with 59 bays combined. If we all had to do it over again we would. We run bug cleaner, presoak, spray wax, hp rinse, hp soap, and spot free rinse. We didn’t bother with triple wax or foam brush because it would have required more high pressure valves to replace simple air operated delivery systems.

Pros:
Variable Frequency Drives (VFD’s) with a pressure transducer (allows the VFD to know the delivery pressure) with a programmable logic controller (PLC) enable you to run any pressure for the controlled functions. We love delivering spot free rinse at 400psi instead of 200psi. We also have a power boost button that allows the customer to switch from 1000psi to 1400psi while using rinse or soap. Our pumps run around half the speed (33hz) to deliver 1000psi and about 75% (44hz) of full speed to deliver 1400psi. We are saving energy. If the customer puts the gun away running the pump slows down to around 15hz. Your equipment room is quieter too. Running pumps slower extends their life.

Our low pressure products are delivered within 8 seconds using a stainless steel air operated ball valves. We run a ¼” high pressure hose for the top of each bay back to the equipment room to the ball valves. We open it when the customer switches to a low pressure function and dump it to the drain. The VFD runs at full speed and rushes the low pressure product to the customer. The customer feels about 100psi during the changeover. The valve closes slowly and the VFD slows the pump down so there is a gentle transition.

Since very few operators are doing this so you can deliver a better and unique washing experience to your customers compared to your competition.

Cons:
You’re adding more components to deliver this experience. VFD’s, pressure transducers, PLC, high pressure pump inlet valves and dump valves are required.

There’s a lot of expense associated with this stuff even if you build it yourself. Just like anything expensive you should visit locations that have it installed and talk to the car wash operator or better yet their attendant and ask them about it.

 

[MEP001]

I've been wondering about another "con" - doesn't it end up wasting a lot of chemical with the purge? It seems like a 3/8" line full of tire cleaner dumped down the drain many times a day would really add up.

Ours is a "traditional" car wash with some inexpensive modifications I've done myself - spot-free is delivered to the bay at 450 PSI and low-pressure changeover at the gun is down to about 4 seconds with no waste through purge.

 

[Bubbles Galore]

4 seconds? Really? That's phenomenal! Please share.

 

[MEP001]

I've used an output from the programmable relays in each bay to purge the bay hose with air after each use. It's the water in the hose that causes the usual delay, but with the bay hose empty the tire cleaner/presoak gets to the tip right away and without any water coming out first. The spot-free delivered through a separate line to the boom at 450 PSI gets to the gun in two seconds.

 

[thoffmanjr]

Regarding the tire cleaner waste from purging you’re right that there is some waste but having everything coming out of the gun from the high pressure pump except tire/engine cleaner didn’t appeal to me.

I like the idea regarding pushing the liquid out of the line using air after the bay is used. Reminds me of a feature we have. While the customer is using the foam brush, wheel scrubbing brush or the triple wax gun the VFD runs the pump at 75psi on rinse to clear the high pressure hose so when the customer returns to rinse they don’t have to waste any time waiting for the line to clear. The pump is barely running and doesn’t go past 5hz.