Reversed Duck Bills?

[abalmuth]

I had a problem with one of our Vacuflush heads this past week.
The Vac pump would not turn on unless I manually move the pressure switch and then it would only work for a short while, the system would flush once and then I needed to move the switch again.
Oh Sh!t, I need a $150.+ switch!
Well for the heck of it I took the pump apart to look at the duck bills, my S-Series vacuum pumps use 4 duckbills, and found the two outboard duckbills inverted – they were facing the opposite direction from the way they were installed.

I got new duckbills(from boatfix), installed them – the right way- and all is working fine
Has this happened to anyone and do you know what caused the outboard duckbills to get inverted?

 

[SLW]

Restricted tank vent would be my guess.

 

[PascalG]

you dont' really need to take the pump apart, just unscrew the hose fittings... that's the beauty of FV

i've heard that using a plunger can resutl in inverted DBs but i've used plungers before with no issues. they are so close to each other that I dont' see how there is ever room for the DB to flip around.

 

[abalmuth]

Pascal
My S-Series vacuum pumps are mounted on top of the Vacuum tank- “VacuFlush vacuum generators combine the vacuum tank and vacuum pump in one unit.”
So the pump has to be removed from the tank to get to both sets of valves

 

[SLW]

A plunger would have to invert the upstream DB's before it could invert the downstream ones...

If the tank vent is restricted, then the tank could hold pressure. The next upward cycle of the pump sucks the downstream DB's inward.

 

[PascalG]

well, because the DB are very close to each other, they the tip of the the first one gets into the back of the next one. I guess the first one can invert, bu i dont' see how the 4th one could within its tip hitting the tip of nr 3

I see what you mean about having to remove the pump... mines are stand alone vac pumps / vac tanks so i can just undo the fittings.

 

[SLW]

Pascal, I'm not sure what you mean by there not being room to flip?

 

[SLW]

oops - sorry. I deleted and re-posted because I originally stated if a tank where under vacuum, when I meant to say pressurized.

they have that collar which probably doesn't give much, so my guess is that there's plenty of room. Of course, they probably suffer "inversion" at the same time, thus eliminating the space issue.

 

[pdecat]

if you left the dump valve open water pressure from running at warp speed could invert the outboard duck bills.

Hummm Duck bills,, nooooo I guess i better not go there.

 

[abalmuth]

quote:

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Originally posted by pdecat

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Hummm Duck bills,, nooooo I guess i better not go there.

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Bruce,
you are getting wise!