inject soap into water line

[Trickyrick]

I had a project that I made to add laundry soap to the washer when my wife starts up the washer.
I want to no use the same type of pump (Peristaltic) to try to inject dish soap into the waterline just before the sink taps. Not sure how to do this as the water line is about 45 lbs I think it would feedback through the pump.  I could add a check valve but don't think the pump would be able to force the check valve open with 45 lbs pressure on the other side
Any ideas
Thanks

[PerryBebbington]

In the UK that would be illegal as you would potentially be contaminating the water supply.

[Trickyrick]

Well I could put a check valve  in the water line going to the tap so that would prevent anything from flowing backward

[Paul_KD7HB]

How would that work when you want plain hot water to wash your hands or plain hot water to rinse a dish?

Paul

[dougp]

Well I could put a check valve  in the water line going to the tap so that would prevent anything from flowing backward

I think air gaps are preferred.

#notaplumber

[Paul_KD7HB]

Research "bernoulli pump" and see if that would not be a better answer to your project.

Paul

[aarg]

Well I could put a check valve  in the water line going to the tap so that would prevent anything from flowing backward

...and if your check valve, which has never been tested or specified for that particular application, fails or does not provide the expected level of isolation?

[TimMJN]

If you want to inject something into the water line (which doesn't sound like a great idea btw), you need to generate a pressure larger than the water pressure. That's fluid dynamics 101.

Why doesn't you run a little soap line alongside the water line in your tap, and then have the soap come out at the exit of the tap, together with the water? It sounds a bit easier and definitely safer to me..

[bluejets]

There are non-return fittings which screw on to the tap.
Used in Aus all the time , primarily to stop any of those nasty garden weed poison bottles from contaminating the main supply.

https://sunshoweronline.com.au/pipe-fittings/brass-valves-fittings/brass-check-valves/brass-vacuum-breaking-check-valves-1?gclid=EAIaIQobChMI4YSww8_I6QIVRaWWCh1AmAZrEAQYAiABEgIBV_D_BwE

BUT, as mentioned, you cannot feed into a 45psi line with less than 45psi, it'll simply fill your detergent bottle.

Dishwasher detergent is not suitable for washing clothes by the way.

Most machines will have an air brake chamber where the tube could be located, basically gravity pressure there.

[Paul__B]

In almost all legislatures, a check valve would not be considered acceptable to prevent back-flow of a potential contaminant.  

The project is pointless, you simply need a separate dispensing nozzle.  

[AJLElectronics]

"The project is pointless, you simply need a separate dispensing nozzle.  "

Even Mother Nature worked that one out. ;-)

[Paul__B]

Even Mother Nature worked that one out.  

Not sure what you are describing here. ...  

[Trickyrick]

Thanks, guys for your input
I'm going with TimMJN suggestion with a separate line for soap

[evanmars]

Venturi

[bluejets]

In almost all legislatures, a check valve would not be considered acceptable to prevent back-flow of a potential contaminant. 

 

Best you inform the Australian building code department of your concerns then because, as it stands, the fitting I linked to is mandatory and for the reason given.