Wednesday, July 31, 2024

A longer Lasting Joker Valve

11-30-2012, rev. 7-31-2024

Every sailor with a manual head knows that the joker valve is the check valve at the bottom of the head, the one that everything has to pas through, the one that must be changed every 1-2 years, and... the place you will find most clogs.


This time of year folks start talking about winterizing and what they pour in or how they drain out to prevent ice damage. Sometime I hear of things I know are damaging the head, and I just cringe. A resent letter-to-the editor of Practical Sailor got me thinking; we haven't reviewed joker valves and the details.

The Problem: Not all valves do well with chemicals, and few last as long as we'd like.

Don't worry; this will only happen if you use Lysol in the bowl... which a few people do.
 Also, some head treatments contain formaldehyde (stinky blue stuff) and will do the same thing if not well flushed. Ban these from your boat



This Jabsco valve (left) saw only waste and ethylene glycol and lasted 5 years. A valve in this condition actually leaks less than you would expect; although it is gaping, the lips are smooth and the back pressure holds them together. Occasional use of vinegar keeps the lime at bay. The head itself is 16 years old, though I replaced the pump assembly at 13 years (like new now).


First, all common joker valves are dimensionally interchangeable. Yup, Raritan, Jabsco, and Groco all use the same basic dimensions. However, they differ in some molding details and use different rubber compounds. The correlation, of course, is that their chemical vulnerabilities are different and that no single chemical compatibility list will cover all heads. Some are not compatible with vegetable oil, while some are. Some are not even compatible with propylene glycol, though the PG manufacturers would tell you their product is safe for everything.

Propylene glycol can be rough on other parts as well. While PVC and polyethylene do very well, my clear potable water strainer crazed in just 2 winters. Though they were good about replacing it, I just leave it off in the winter now.


Testing: So I lined up bottles in the lab, filled with common joker valves and common chemical concoctions. After 3 months I measured stiffness and leak resistance. And guess what; some were more compatible with winterizing chemicals than others. Some were more resistant to urine than others.





 Then I donated a bunch of valves to friends, both live-aboards and weekend sailors. I waited to hear which valves failed first, and which lasted for years.

Head Manufacturer    Material        Urine Compatibility      Durability (years)   Comments
Jabsco                        Neoprene       Excellent                           1-3
Raritan                       Nitrile            Good                                  2-5
Groco                         Nitrile            Good                                  2-5                     Hard to pump (stiff)
 

Solution: Raritan pH II valves fit Jabsco manual heads and last nearly twice as long. They withstand propylene glycol antifreeze without complaint. They fit perfectly. Yes, they do cost a few dollars more, but less in the long run, and who likes working on heads?

I still use ethylene glycol in my head (automotive antifreeze), even though the Raritan valve can handle it. Why? There are additional neoprene parts in the Jabsco head (flapper and o-rings), and I'm not really all that worried about anyone drinking out of my holding tank.

What about the flexible impeller pumps for raw water and potable water? Some of the raw  water pumps are nitrile and are thus immune to propylene glycol, but some are neoprene. After all, neoprene has a better flex life. There have been reports of PG damaging raw water impellers over the winter, ever since we bought into this well intentioned but wrong conventional wisdom that PG is better for the environment than EG (link). For this, I blow out as much of the PG and hope for the best. So far, so good.

Tip of the day? Winterize all non-potable systems with ethylene glycol.



8 comments:

  1. I am very interested in what you find, as I have two jokers to replace - right now! - according to Jane.

    Besides the usual, only vinegar and salad oil go in our heads. Any recommendations?

    bob

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  2. If it's a Jabsco head, Skip the oil and lube with synthetic grease by opening it up. That is what the manual states, because the salad oil is a no-no for neoprene joker valves. Other brands can better tolerate the oil.

    If you must use oil, only soy bean or canola oil; olive oil is not good and corn oil is worse.

    But oil in general can also be an odor problem; because it floats on the surface it prevents air transfer into the holding tank and promotes anaerobic conditions, leading to stink. Sewer authorities restrict oil and grease (including vegetable oil) to about 100 ppm because of sewer clogging and treatment problems.

    -----

    So much misinformation out there, often from authoritative sources but in conflict with the manual.

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  3. How do you winterize your head, Drew? Do you use the pg stuff?

    Rick - s/v Cay of Sea - just down the creek from you.

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  4. Mid-Chesipeake-specific comment:

    Yes, I do winterize the head. Though it seldom gets that cold, I have frozen water bottles a few times and did break one pipe fitting the first year I had the boat. The prior own said "just blow it out," but he lived in Deltaville. I later found additional signs of repairs; he'd busted a few things and just didn't want to talk about it. I've had no issues since.

    This post (http://sail-delmarva.blogspot.com/2012/10/easier-winterizing.html) describes the specifics. I also flush with weak EG through the winter, to keep the tank and bowl freeze-proof. We just keep a jug with 20% EG in the head.

    I have always used EG on the blackwater system and never suffered any material compatibility issues. Joker valves last a few years.

    Yes, I use PG on the potable system. This rather long post covers antifreeze and why EG is no more toxic in the Bay than PG.
    http://sail-delmarva.blogspot.com/2009/11/marine-winterizing-antifreeze-and.html

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  5. Nice article... Although you have been misinformed about your "nylon potable water strainer bowl". That is definitely not nylon, as nylon is never clear and nylon (with few exceptions to rare solvents) never "crazes". The material of that bowl I could guess at (I'm a plastics guy), although it wouldn't matter at this point. But that strainer bowl is NOT nylon.

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  6. ^^ So right you are. The based is nylon and the bowl is probably styrene-acrylonitrile (SAN), though I could not get a straight answer from the maker.

    What caused the stress cracking? While there are many agents that could be responsible, in combination with mechanical stress, we may never know. What does seem clear is that the failures correlate with polypropylene glycol winterizing agents.

    Nylon bases are also susceptible to cracking when winterized with PG. EG does not seem to have this effect.

    ReplyDelete