Valve

Which type of pump? What it handles? What capacity/size? Witout these informations answers will be like throwing arrow in dark.

However, the most general answer is- the check valve is meant for preventing backflows from discharge pipe when pump is not in operation. In case of multiple pumps installed in parallal, liquid backflow will be disasterous, as it will bypass some pumped liquid to suction again. Liquid backflow may also cause reverse rotation of impellers in case of centrifugal pump.

Pritam gives a correct answer and the best description of the need for a check valve.

However, I would like to add:

- The damage that can occur if reverse flow occurs within a pump includes impeller disengagement (unscrewing the impeller) and seal damage

- It is possible to run A SINGLE PUMP with no check valve and a shutoff valve upstream and downstream of the pump. As stated above, disaster can occur if multiple pumps in parallel without check valve protection.

1. Check valve prevents backflow of liquid.
2. Butterfly or ball valves isolate the pump when not in use or when undergoing servicing.

And to add to the Dark Lord's comment, the Check valve has an occasional malfunctioning capacity (sealing on those times are not 100%).

This creates some problem when you try to take out the standby pump for repair with the other running.

Why indeed. There are numerous applications where a check valve is never required.

And numerous applications where a valve at the outlet of the pump is not required, either.

OHH! Lynlynch,

Please, you are not just going to leave us hanging here like this are you???

Give us some valid examples of a centrifugal Pump Installation where the pump is fully piped into a system but does not need a check valve and or an outlet block valve.

"fully piped into a system" is a horse of a different color.

A submersible pump for an ornamental fountain comes to mind. All it needs to do is to force water up through a series of nozzles to form a spray after all.

PCB fab equipment pulls fluid from a sump and pumps it into a spray bar system to develop and etch circuit boards. Turn the pump off and everything drains back in to the sump.

In fact there are many oem applications for small centrifs (or other pump types), especially closed-circuit in heat-transfer, such as coolers/chillers for lasers, x-rays, semiconductors, etc where there are no valves whatsoever. For pumps in general, type/quantity/location of valves is specific to pump types and applications. There is no general rule, and too many variations to be more specific here.

Dear All,

WATER WELL, PUMP, & TANK CHECK VALVES

Our photos above show a tpyical brass well piping check valve. A spring-loaded internal valve permits water to flow through the valve only in one direction. The check valve helps assure that the jet pump can suck water out of a shallow well - most water pumps cannot move water if the inside of the pump assembly itself is air bound. Atop some pump assemblies you'll see a removable pipe plug which permits water to be poured into the pump to prime it. (DO NOT pour water into or onto the electric motor itself.)

In summary, a well piping check valve prevents water from siphoning back out of the water tank and water pump and down into the (presumably lower) water well when the pump stops running.

A check valve at this location is a great idea and reduces the risk that a failure of the foot valve down in the well leads to inability of the pump to draw water. The foot valve s located at the bottom of the well piping and intended to accomplish the same thing. This is "cheap insurance" or perhaps the foot valve has already failed (or was omitted) at this installation.

Check Valves on Municipal Water Supply Piping

You may see check valves installed on municipal water supply piping too, to prevent possibly unsanitary water from inside a building's piping from back-flowing into and contaminating the municipal water supply system piping during a time of loss of municipal water pressure.

Check valves installed at the right location on water system piping are a good idea and are required by national and local plumbing codes in many jurisdictions.

Check valves are also installed on drain piping such as on some sewer lines (where sewer backups are likely) and on sump pumps (discussed below).

Other Applications of Check Valves on Building Plumbing & Piping

Check valves on sump pumps: Check valves are used in other plumbing applications as well, such as on sump pump drain lines to prevent back-flow of water from the sump pump exit piping into the sump pit when the sump pump turns off.

Regard's

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