Dear Mr m.qaredaqi

Totally depends on the location of the check valve in the diagram.

Keep in mind that a check valve is a passive element and that a butterfly valve needs to be operated.

And a check valve is cheaper than a controlled butterfly valve.

Also choose the right type of check valve for the intended function.

When the check valve is located on the immediate intake of the vacuum pump, it is meant as the final safety valve and a disc-check valve is the best choice.

Check valves that can come into contact with material do not function for a long time, as they start leaking quite soon after mounting, because material will get stuck between the closing surfaces.

These check valves are backed up by a butterfly valve anyway (if controlled properly)

Have a nice day

Teus ■

Originally Posted by m.qaredaqi

hi every body

is a butterfly valve suitable for replacing instead of a check valve in a vacuum pump pipe?

I would say NO.

The two are completely different types of valves. A check valve is an automatically operated valve that allows flow in one direction only. A butterfly valve is simply a valve that can shut off flow.

A check valve operates automatically and is completely self-contained in its operation. It relies on no external source of power to operate or sense flow direction.

A butterfly valve requires external actuation and external sensing and would not be classed as a check valve.

This begs the question "Why do you want to replace a check valve with a butterfly valve? From a cost point of view, I would have thought that a butterfly valve with all the actuating and sensing would be more expensive than a check valve. ■

Originally Posted by m.qaredaqi

hi every body

is a butterfly valve suitable for replacing instead of a check valve in a vacuum pump pipe?

This is another indication that you have got into trouble with your drum filters.

Explain your application. Just how are you mounting a check valve in a vacuum line?■

A check valve is mounted in a clean vacuum line in such a way that, when the vacuum pump drive fails, the existing system vacuum is not able to make the vacuum pump rotate backwards.

A check valve in a (clean) vacuum line is especially important in case more vacuum pumps are working in parallel.

Have nice day

Teus ■

Originally Posted by m.qaredaqi

hi

thanks for your attentions

the problem is about a filtering system. drum filters with Dor Oliver brand (extra heavy duty drum filter) for dewatering of iron slurry. 3 vacuum pump and 3 vacuum tank with mother collecting tank connected to each other. because of suspicion to bad performance of check valves, it decided to replace them with butterfly valves to eliminate probable leakage.

What type of check valve are you having problems with at the moment? ■

Originally Posted by m.qaredaqi

swing check valves.

it's been thought that air leaked from this valves and it's caused to not sufficient vacuum.

Get in touch with the technical department of the valve manufacturer and seek their advice. After all they have designed it.

Swing check valves may not be suited to your application, and are normally used where there is a positive reverse flow. There also has to be a minimum reverse flow for them to work without leaking. This reverse flow is related to their size. You also need to look at the normal state flow when selecting the valve. Also make sure the manufacturer knows how it is to be used.

Your considering a butterfly valve replacement is merely having a positive actuation at a set low reverse flow.

I would be looking into something like a spring return check valve. This way you will get positive seating with a minimum flow required to open it. A swing check valve is very sensitive to operating position and relies on the weight of the mechanism to shut off reverse flow. ■

Whatever happened to the vacuum breaker legs which were always installed in suction filter lines? They were still being recommended in W Oz as recently as 2008. It would seem that your original installation mounted the filters too low. ■

Dear Mr m.qaredaqi

Listening with a stethoscope at the suspected check valve could give you an indication.

A too low vacuum can also be caused by a worn out blower, causing too much internal leakage or a leakage somewhere else.

Check the installation physically.

Good luck

Teus ■