self priming centrifugal pump limitations
self priming centrifugal pump limitations
(OP)
I am trying to decide if I can accept a vendor proposal to use a self priming centrifugal pump instead of a vane pump.
The application is for diesel unloading from trucks. Gravity draining is not an option. An air eliminator downstream of the pump will be used.
The concern I have is that the self priming centrifugal may not be able to perform a suction lift from a partially full tanker when the suction line is empty. If the suction line is empty, the air volume may be much larger than the priming chamber. The suction line is estimated to be 10 to 20 feet of 4" pipe and hose with a strainer, some valves, etc.
Is this air volume typically a problem, or will a self-priming centrifugal typically be able to prime itself independent of the suction air volume?
The application is for diesel unloading from trucks. Gravity draining is not an option. An air eliminator downstream of the pump will be used.
The concern I have is that the self priming centrifugal may not be able to perform a suction lift from a partially full tanker when the suction line is empty. If the suction line is empty, the air volume may be much larger than the priming chamber. The suction line is estimated to be 10 to 20 feet of 4" pipe and hose with a strainer, some valves, etc.
Is this air volume typically a problem, or will a self-priming centrifugal typically be able to prime itself independent of the suction air volume?





RE: self priming centrifugal pump limitations
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: self priming centrifugal pump limitations
I am trying to find out if there is typically any limit to the air volume one of these pumps can handle while priming. Does this chamber fill with air, or will the liquid keep recirculating until it's primed?
RE: self priming centrifugal pump limitations
RE: self priming centrifugal pump limitations
Thanks for that clarification. It's exactly what I was trying to find out.
RE: self priming centrifugal pump limitations
How about using a double diaphragm pump? Those pumps can move super viscous liquids and pasts even in cold weather. I think that would be ideal for your diesel. They have electric, water, and air driven double diaphragm pumps. But those things will self prime very easily, even if there is a lot of air or a leak. Plus it's a positive displacement pump, which means your diesel will always move forward.
Is flow pulsation an issue for your application? Buy a large pulsation dampener.
RE: self priming centrifugal pump limitations
I didn't look to diaphram (or double diaphram) pumps because I'm looking to move around 300 gpm. I don't know many diaphram pumps with that kind of capacity.
Positive displacement pumps are generally good for my application because most of them are good at self-priming. However, the piping system also has to handle the pump as a potential source of overpressure. In this case a relief valve routed to the pump suction will serve this purpose. Additionally, a low flow switch will be used for shutdown to protect against overheating/seal failure.
Thanks to all for your replies. I think I have what I need on this issue.
RE: self priming centrifugal pump limitations
235 gpm, aluminum pump, 9948K24 $2,219.24
235 gpm, stainless steel, 41655K32 $4,713.04
*Note, these require 100 CFM of compressed air.
If you contact a local double diaphragm pump dealer, you can get one to do 300+ GPM. And you can buy something with an electric motor running it. If you can supply that much air, my favorite pump is the Sandpiper from the Warren Rupp. That bad boy will pump rocks and marbles if necessary.