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.