Does anyone know the volume per stroke on a Jabsco manual head? Trying to figure out how many to clear the line.
Jabsco volume per stroke
- Thread starter robinrjellis
- Start date
Excellent particulars to ponder while sitting on the head. I spent many years dealing with leaks on a Jabsco but have since deep sixed all previous parts after going to a Raritan.
You're going to have to pull the piston and measure the OD of the piston ring or if you can live with something a little less precise, measure the OD of the cylinder and subtract 1/16" for wall thickness to get the OD of the piston ring.
Area of piston ring X length of stroke = displacement of the piston
You're going to have to pull the piston and measure the OD of the piston ring or if you can live with something a little less precise, measure the OD of the cylinder and subtract 1/16" for wall thickness to get the OD of the piston ring.
Area of piston ring X length of stroke = displacement of the piston
Best way to find out is to count. However, that actually depends on how old your joker valve is, 'cuz most people think that the only thing the joker valve does is acts as a check valve to stop backflow from returning to the toilet or odor from the tank from escaping through the toilet. But that's the joker valve's LEAST important function...in fact, the joker valve is THE single most important replaceable part in a manual toilet. Here's why:
On the upstroke of the piston, a vacuum is created in the area beneath the piston. This causes the joker valve to close tightly, and the flapper valve beneath the pump to open, allowing some of the contents of the toilet bowl to be drawn into the bottom half of the pump. Then, on the down stroke of the piston, the flapper valve is slammed shut, and the effluent is forced out of the bottom of the pump, through the joker valve, and off down the line. But when the joker valve becomes worn and/or there's a buildup of sea water minerals on it, it can no longer seal tightly on the upstroke of the piston so less and less vacuum is created, requiring more and more pumping to move bowl contents.
You prob'ly won't notice the loss of efficiency at first because it's so gradual. But I guarantee you that if it's been two years or longer since you replaced the joker valve, you need to pump the toilet at least 50% more times to move the bowl contents to the tank or all the way out the thru-hull....IF they're getting there at all any more.
So unless your joker valve has been replaced recently, just for fun count before you replace the joker valve and count again after you've replaced it. I think you'll be surprised by the difference.
The path the toilet discharge line takes also matters. If it's short, straight and downhill--getting some help from gravity, it will require fewer pumps than a line that's longer than 6' (the max distance most manual toilets can move bowl contents in a single pump) and/or has bends or goes uphill.
--Peggie
Just further reading:
The geek in me popped out so I measured stuff. It turns out that for every stroke. The liquid would move about 5 inches down the 1.5 inch sanitation hose.
piston is 1.665 inches , stroke is 5 inches. The little “twist and lock” cone takes up a little volume in the pump, and the pump won’t be 100% , so a good estimate is that every 5” stroke pushes 5” of liquid down the line. Once it starts pushing air, the displacement will be a little less.
The geek in me popped out so I measured stuff. It turns out that for every stroke. The liquid would move about 5 inches down the 1.5 inch sanitation hose.
piston is 1.665 inches , stroke is 5 inches. The little “twist and lock” cone takes up a little volume in the pump, and the pump won’t be 100% , so a good estimate is that every 5” stroke pushes 5” of liquid down the line. Once it starts pushing air, the displacement will be a little less.
This is great. Your comment got me thinking generally about toilet maintenance and led me to a blog post at Jamestown Distributors who offer this:
- When the bowl is empty, Open (
) the Flush Control again, and continue to pump until all waste has either left the boat, or reached the holding tank (allow 7 complete up/down strokes per metre (yard) length of discharge pipework).
No! Plunging any marine toilet except a VacuFlush can mis-align the seals, o-rings etc in the pump, creating an even bigger problem.
Not all "clogged" toilet discharge lines are actually clogs. Flushing against a blocked tank vent can pressurize the tank, creating back pressure that'll prevent the bowl contents from going anywhere. Don't us the toilet again or attempt to pump out until you've cleared the vent. I've posted instructions for doing that several times...they're also in my book. Sea water mineral buildup in the toilet discharge line can reduce the diameter enough to create what feels like clog...I've seen it reduce the diameter of a 1.5" hose to less than .5" A weekly cupful of distilled white vinegar used according to directions will prevent it...Muriatic acid used according to directions is the cure. If someone has flushed a wet wipe, it may have clogged the toilet pump...surgery will be required.
Actually the number of pump strokes needed to move bowl contents all the way to the tank is variable depending upon how much help the toilet gets from gravity, the toilet discharge line routing, amount of seawater mineral buildup in the toilet discharge line, whether the pump is in need of lubrication and even the make of the toilet. For instance because a Raritan PHII has a larger diameter piston, it will pump twice as much per stroke as it's competitors will. Adding the lever-type handle, there isn't as much actual effort required. So, you only have to pump half as many times to flush it, and your arm doesn't get as tired. Plus, with the lever handle, you don't have to bend over as far, with your nose practically in the bowl, while you're pumping it. Maintenance matters too...see post #3 for my explanation of how the condition of the joker valve impacts the number of pumps needed by any manual toilet.
I strongly suggest y'all check out my book (see link in my signature below) Its title (my publisher's idea) is a bit misleading...'cuz although it does deal with every source of odor on a boat and how to cure, or better yet PREVENT 'em, it's actually a comprehensive "marine toilets and sanitation systems 101" manual that explains the laws, describes all the types of systems and how they work, and will help you learn how to operate and maintain your system to prevent 99% of problems instead of having to cure 'em. 'Cuz you get to do any preventive maintenance on your terms when it's convenient...the need to cure a problem never happens when it is! And you already know that I'm always glad to answer any questions it doesn't.
--Peggie
Not all "clogged" toilet discharge lines are actually clogs. Flushing against a blocked tank vent can pressurize the tank, creating back pressure that'll prevent the bowl contents from going anywhere. Don't us the toilet again or attempt to pump out until you've cleared the vent. I've posted instructions for doing that several times...they're also in my book. Sea water mineral buildup in the toilet discharge line can reduce the diameter enough to create what feels like clog...I've seen it reduce the diameter of a 1.5" hose to less than .5" A weekly cupful of distilled white vinegar used according to directions will prevent it...Muriatic acid used according to directions is the cure. If someone has flushed a wet wipe, it may have clogged the toilet pump...surgery will be required.
Actually the number of pump strokes needed to move bowl contents all the way to the tank is variable depending upon how much help the toilet gets from gravity, the toilet discharge line routing, amount of seawater mineral buildup in the toilet discharge line, whether the pump is in need of lubrication and even the make of the toilet. For instance because a Raritan PHII has a larger diameter piston, it will pump twice as much per stroke as it's competitors will. Adding the lever-type handle, there isn't as much actual effort required. So, you only have to pump half as many times to flush it, and your arm doesn't get as tired. Plus, with the lever handle, you don't have to bend over as far, with your nose practically in the bowl, while you're pumping it. Maintenance matters too...see post #3 for my explanation of how the condition of the joker valve impacts the number of pumps needed by any manual toilet.
I strongly suggest y'all check out my book (see link in my signature below) Its title (my publisher's idea) is a bit misleading...'cuz although it does deal with every source of odor on a boat and how to cure, or better yet PREVENT 'em, it's actually a comprehensive "marine toilets and sanitation systems 101" manual that explains the laws, describes all the types of systems and how they work, and will help you learn how to operate and maintain your system to prevent 99% of problems instead of having to cure 'em. 'Cuz you get to do any preventive maintenance on your terms when it's convenient...the need to cure a problem never happens when it is! And you already know that I'm always glad to answer any questions it doesn't.
--Peggie