Need good quality but inexpensive in line check valves

[mobeewan]

I need to fix a plumbing mod I did for the black tank. There is a plugged 1/2 NPT female connection on one end and one side of the tank. I removed the plugs and made and mounted a manifold with 2 ball valves next to the dump valves. Each valve has a hose running to a tank connection. At each connection I added a 1/2 NPT elbow with a 1/2 NPT plastic inline check valve.

What I did works pretty well for flushing and rinsing the tank. However, the check valves springs are only rated at about a half pound. When setting while camping and the black tank is being filled, there is no pressure to keep the check valves seated. This causes black tank water to seap back through the check valves and back down the hoses to the manifold. Since I originally didn't expect the check valves to leak I used PVC for the manifold and ball valves. In freezing weather a PVC fitting cracked and dripped black tank water.

The brass check valves for the water heater outlet and city water hookups are also pretty weak ruling them out for my use.

I looked for decent quality brass check valves with NPT threads and springs rated at about 5 lbs. This would be more than enough spring pressure to keep the valves seated and stop back flow from the black tank. The only ones I could find we're pretty expensive at over $50 apiece.

I am not going to replug the connections and add tank rinsers. As I indicated it works well except for the back leakage through the check valves. Better valves will solve the problem.

Does anyone know where I can find any brass inline check valves with at least 5 lb springs that are cheaper?

[mobeewan]

Nothing to fix, I need new valves.

[Kennedycamper]

One thing to try, if you can open the check valve up stretch or replace the spring to make more tension.

[mobeewan]

I need something like this Parker check valve. But I don't want to pay $46 to $71 a piece for two of them.

[mobeewan]

The springs are only about a half pound and maybe even less. I suspect the tank contents are splashing back through the elbows and against the valve seat. Either that or once the tank contents get above the connections it just seeps back through the check valves because there is no positive seating. The 1/2 pound springs are not much of a positive seat. The valves I bought are actually plastic and I think made by Qest. They are used on trailer water heater outlets and work the same as the brass valves. The valves should be good for 60 to 100 PSI. However I don't have 60 to 100 PSI to backseat the valve hard against the seat. So the liquid contents of the tank seap back through the valves and down the hoses to where you would connect a garden hose to flush the tank. Not very sanitary when connecting the garden hose or in my case when the contents froze and cracked the PVC nipple at the ball valves.

[prichardson]

Do you have something creating pressure on the inlet side of the check valve preventing it from closing or trash in the valve? In the check direction the fuller the tank the tighter it will close. Pressure ratings are what it takes to open the valve from the inlet side.

[mobeewan]

I've looked at McMaster Carr and Grainger, as well as many other places. As I originally stated I have found what I'm looking for but they are pricy at over $50 each. I may go that route, but am trying to save some cash.

Thanks for the suggestions of where to look, but I'm looking to see if anyone has knowledge of an inexpensive source instead of where I might find what I need. I'm not trying to get others to look for me. I'm just looking for help from someone that already knows a good source. I was hoping to find that plumber or handyman that could tell me where they new I could find a cheap source.

[mobeewan]

Captain_Happy wrote:
ON some RV's the check valves off the water heaters are metal ones. On my Forest River 5th wheel trailer, the 10 gallon water heater has the metal 1/2 NPT screwed right into the water heater female inlet & outlet fittings and the water lines fittings screw into them.

Now I also have a Casita trailer with a 6 gallon water heater, and the check valves look like brass heavy duty check valves.

NO matter what you do, which I think you've already figured out is, your going to have to get away from the plastic ones because cold weather.

I'd start by looking on Amazon first, and then an RV parts store. Good Luck.

The springs are too weak. I've already mentioned it in my OP.

[mobeewan]

RLS7201 wrote:
Factory installed flushing check valves are mounted higher than the top of the black tank. Is this possible for your coach?

Richard

No. It's a TT with exposed grey and black tanks

[toddb]

try www.mcmaster.com

[Passin__Through]

If you have the space available you might try putting a second plastic check valve in tandem with each of your existing check valves. This double-check setup could solve your problem very inexpensively.

In my prior life I worked in an oil refinery and saw many, many tandem check valve setups in various piping systems.

Hope this helps.

[RLS7201]

Factory installed flushing check valves are mounted higher than the top of the black tank. Is this possible for your coach?

Richard

[midnightsadie]

might look in the grainger book.

[Captain_Happy]

ON some RV's the check valves off the water heaters are metal ones. On my Forest River 5th wheel trailer, the 10 gallon water heater has the metal 1/2 NPT screwed right into the water heater female inlet & outlet fittings and the water lines fittings screw into them.

Now I also have a Casita trailer with a 6 gallon water heater, and the check valves look like brass heavy duty check valves.

NO matter what you do, which I think you've already figured out is, your going to have to get away from the plastic ones because cold weather.

I'd start by looking on Amazon first, and then an RV parts store. Good Luck.