Stainless Zerks Sealed to Resist Grease Pushing Out?

[Chips O'Toole]

I have an unusual question.

If you have a pool, you know the filter and pump parts are made of cheese. Overpriced, and designed to fail. This week I learned that the valves on my pool have incredibly flimsy grease fittings on them. They basically dissolved in chlorinated water. They fit in 1/8" NPT holes in PVC. There are knobs on them, and they're full of grease. You turn the knobs to push grease into the valves.

These parts, made by the Jandy company, are worthless. I was thinking I would just replace them with stainless zerks which only cost a few cents each.

Someone pointed out that the zerks might leak water when the pressure was on.

I'm buying a box of zerks anyway. They only cost $13 for several dozen, and they can be useful elsewhere. Is there such a thing as a stainless zerk which is made to resist internal pressure so the grease doesn't back out?

The alternative is to use NPT plugs. I can remove the plugs occasionally, put the zerks in, shoot grease in, and replace the plugs.

 

[JimDawson]

Normally there is a spring loaded ball in a zerk that prevents the grease backing out.

 

[Chips O'Toole]

Just wondering if it will resist water pressure.

 

[JimDawson]

It should. Best way is just to try it and see what happens.

 

[MrWhoopee]

That sort of pump pressure is generally low, less than 100 psi. Shouldn't be a problem.

 

[Ulma Doctor]

a zerk fitting is basically a check valve capable of handling hundreds(if not thousands) of pounds of hydraulic pressure
the more reverse pressure exerted on the check ball, theoretically, the more the check ball will seal against its seat.

 

[Nutfarmer]

Make sure what is to be used for lubrication. A lot of times in pool valves and equipment they use a silicone type grease and assembly lub . Yes the pool parts are just cheap plastic and not cheap to replace.

 

[ErichKeane]

I note that mcmaster has 2 separate categories of Zerks, one of which is a 'leakproof' (https://www.mcmaster.com/zerk-grease-fittings/leakproof-grease-fittings/). Quoting that:

Keep thin grease from leaking out—the check valve in these fittings has a Buna-N seat that creates a tighter seal than check valves in other grease fittings. The valve stays closed when not in use to keep out dirt and other contaminants. Fittings are zinc-plated steel, which has mild corrosion resistance. They're also known as hydraulic grease fittings. They have PTF and NPTF (Dryseal) threads, which are compatible with NPT threads.

You might see if you can find a spec-sheet on the zerks to see how much pressure they are rated for. Typically they dont get more than a few PSI, so I'd wonder if they are designed to take 100 PSI. I cannot find any spec sheets from any manufacturers in a few minutes of googling though.

 

[machPete99]

Sometimes these things require periodic replacement if the internal spring has fatigued and the ball no longer seals.

 

[Chips O'Toole]

Thanks for all the help.

I have a box of zerks on the way. If they don't work, I can try the fancy ones. I have silicone grease the valves like, and I also have a mini grease gun I don't use.

There is another alternative, which is to put NPT plugs in and grease when I feel like it. I don't foresee any need to buy more of Jandy's flimsy, expensive garbage.