# Pressure washer downstream injector adjustable or fixed "10:1"



## JeffW650 (Jun 27, 2009)

I picked up a great, nearly new Cat Pumps pressure washer off craigslist. 3,800 PSI, 3.4 GPM, 9.4 HP Yamaha engine, long wand, 50' high pressure hose, etc. I paid $275 and the thing looks like it was used for maybe 5 hrs so I think it will pay off vs. $55/day for a rental for 1-3 days per year (Plus I'll obviously use it more if it's always available).

Anyway, I know these aren't super precise but it's factory equipped with a fixed ratio 20:1 downstream injector. 20:1 seems like it's going to be a big pain to get ratios right as many of the concentrates I see are assuming a 10:1 injector. I can always dilute concentrates further if I had a "richer" injector but I obviously can't make the solution more concentrated than what's factory available to accommodate this 20:1. It's just threaded on there between the pump and the quick disconnect for the high pressure hose so it would be trivial to swap out. I think I'd like to swap in a 10:1 or better yet an adjustable one. 

Are the threads on the downstream side of the cat pumps pretty standardized? I see most listed with 3/8" NPT male. Is that likely right?

I guess if I had an adjustable one I could test the flow rate with the black tip by timing the fill of a 5 gallon bucket. Then I could adjust the rate of injection to suck 1/2 gallon of solution in the same amount of time (Yielding an approximate 10:1 ratio). Or just do it by feel. If the solution isn't doing the job then crank the knob a bit "richer" until it does the job.
If I buy a fixed "10:1" then I'd just be stuck with whatever the actual output ratio is with my pressure washer + hose + lance + tip combo.


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