Centrifugal Suction Leak Question

Users who are viewing this thread

Gritres

New Member
Messages
56
Reaction score
0
Points
0
Location
nw florida
I've got a centrifugal and a leak on the suction side (small trickle of air bubbles). The drop line is fresh poly, the leak is most likely in the joints between the poly and the pump, however, it's been hell trying to find the leak and I'm redoing joints left and right and running out of shaving cream.

My question is this: if the drain plug on the bottom of the centrifugal didnt have a good seal would that produce a water leak or a suction air leak? Seems like it'd leak water from what I know about the way the pumps work but I've never opened it up to see exactly how the impeller works in there so I'm curious if anyone had any insight.
 

LLigetfa

DIYer, not in the trades
Messages
7,497
Reaction score
575
Points
113
Location
NW Ontario, Canada
A suction leak does not always manifest as a drip when no suction is present. As for the drain plug question, if you loosen it up, does the shaving cream get sucked into the threads?
 

Gritres

New Member
Messages
56
Reaction score
0
Points
0
Location
nw florida
i was trying to avoid empirical testing but i guess thats the only way to know for sure

another question: if i was having cavitation issues at the impeller would i still see the bubbles caused by it in on the pressure side or does the water vapor all condense once it hits high pressure?
 

LLigetfa

DIYer, not in the trades
Messages
7,497
Reaction score
575
Points
113
Location
NW Ontario, Canada
Bubbles are air, not water vapour. The water vapour returns to a liquid state in the absense of a high temperature or vacuum to sustain it as a gas.
 

Gritres

New Member
Messages
56
Reaction score
0
Points
0
Location
nw florida
it's definitely not the drain plug either, it's high pressure and squirts out water when i loosen it. probably my pipe doped galv -> iron
 

DonL

Jack of all trades Master of one
Messages
5,205
Reaction score
72
Points
48
Location
Houston, TX
On a lot of pumps the drain plug will be in a vacuum when the pump is running, and be under pressure when the pump is off.

You could hook up a vacuum gauge to that port and test the pump for suction problems.


DonL
 

Gritres

New Member
Messages
56
Reaction score
0
Points
0
Location
nw florida
just to confirm the test was done while the pump was on. since it's likely toward the outside of the impeller on my pump it makes sense that it's pressure during and after operation.
 

Masterpumpman

In the Trades
Messages
729
Reaction score
1
Points
0
Location
Virginia Beach, VA
Website
www.dci-inc.us
If the pump sounds like it has gravel inside while running, it's cavitation. Cavitation will cause bubbles in the outlet if placed in the bottom of a bucket of water. You could be experiencing a high lift or plugged well screen. To know I usually install a vacuum guage in the suction line. If it reads more than 21 you have a lift problem or partially plugged well point or screen. If the needle quivers, you have a suction leak. Occasionally a pump seal will suck some air if it's a high lift. NOTE: It's a good idea to have the pump as low as possible. In developing countries people with a lift problem place the pump in a pit nearest the water level as possible. Near Alma, Arkansas we used to tie 4 wells together some 60 feet and 10 to 12 feet deep, then install the pump 10 to 12 feet below ground to reduce the lift for irrigation of bottom farm land along the Arkansas River.
 

Gritres

New Member
Messages
56
Reaction score
0
Points
0
Location
nw florida
ya it must just be a small suction leak from heavy lifting, the pump is not making offensive noises. i'd love to dig a pit for extra efficiency but im afraid of it getting flooded. we can get a truckload of rain at once here and be inundated in no time.
 

Ballvalve

General Engineering Contractor
Messages
3,581
Reaction score
45
Points
48
Location
northfork, california
Grey PVC cement is a good alternative to shaving cream, and let it harden. Looks stupid, but it works.

If the barbs are PVC and you didnt sand the cast line off the barbs, that will do suction leaks quick
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks