Check Valve

[luudee]

 

Hello,

 

I am looking for a check valve, 2", swing type.

 

Now, I have seen what's available at the local shops, mostly china made brass variations. 

Those tend to last for a couple of weeks before they break in various ways.

 

I am looking for a better quality variation, preferably stainless steel, swing type. 

 

Any suggestions where a semi-professional variation of a check valve can be obtained in

Thailand ?

 

Again, I have seen and tried almost every brass version, but my 1.5 hp Danfoss pump trashes them all ...

 

Many Thanks,

rudi

 

 

 

[Artisi]

Have you tried Danfoss or Grundfos - check eBay or Lazada 

[kamalabob2]

Luudee:  Have you checked out the specs on the Web site of the Sanwa brand or ANA brand of brass valves made in Thailand. I have had years of service with smaller Sanwa and  ANA brass lever valves at my home in Buriram. They are not expensive, and I have seen these 2" valves installed at a rock quarry where powerful water pressure is generated by Mitsubishi Super Pumps.  The ANA brass valves are made in Thailand. The Sanwa brass valves are made in Thailand. 

[luudee]

 

I have used the ANA variety, they lasted for about 3 weeks. On one the flap hinge

failed, on another the rubber seal came off and kept the valve open. I don't think

I have seen the SANWA before. KITZ lasted the longest so far with over 4 months

in service ...

 

I was hoping to find local options before going to eBay and such.

 

I wonder if there is a stainless steel variety available locally ...

 

Thanks,

rudi

 

 

[Pib]

 

Quote

...1.5 hp Danfoss pump trashes them all ...

 

Is this just a residential water pump operating at a few bars or some high pressure/specialized pump?  

 

If just a typical residential pump heck I have around a half dozen standard issued brass check values in my lines....all valves around 9 years old....none have failed and a few I've had a chance to inspect about a year ago when doing some rearrangement of my pressure pump and storage tank....all looked in good condition internally and were still working fine.   

 

And when you say check valve I'm assuming you mean one-way flow values verses something else?

[luudee]

5 minutes ago, Pib said:

 

 

Is this just a residential water pump operating at a few bars or some high pressure/specialized pump?  

 

If just a typical residential pump heck I have around a half dozen standard issued brass check values in my lines....all valves around 9 years old....none have failed and a few I've had a chance to inspect about a year ago when doing some rearrangement of my pressure pump and storage tank....all looked in good condition internally and were still working fine.   

 

And when you say check valve I'm assuming you mean one-way flow values verses something else?

 

 

 

Sorry, it's a Grundfos, I get these two always confused, specifically, it's a Grundfos CH8-50 pump.
My application is residential, perhaps a bit larger setup than typical.

 

Regardless, the fact that the Check Valves last in your case for 9 years, doesn't help me.

 

The line pressure is about 3.5 bar. When the pump stops and the valve closes, it generates

a very loud bang. There is a lot of force behind it ...

 

I did not design this setup, it was done by somebody who claimed to know what he was doing.

In any case, I am happy with my setup and had it for a very long time, I just want to find

a check valve that will last longer ...

 

Thanks,

rudi

 

[Pib]

Strange...I use a Mitsubishi pump that generates 2.8 bars with my 9 year old check valves. Your 3.5 bars pump really ain't that much more than a 2.8 bars pump.  

 

You may have some backflow/pump impeller kickback through the pump when it cuts off due to pump design or just your piping setup.   To stop/minimize that you may need a check valve on the "discharge/output" side.  Do you also have a check valve on the "discharge/output" side or only on the suction/input side?  

[luudee]

5 minutes ago, Pib said:

Strange...I use a Mitsubishi pump that generates 2.8 bars with my 9 year old check valves. Your 3.5 bars pump really ain't that much more than a 2.8 bars pump.  

 

You may have some backflow/pump impeller kickback through the pump when it cuts off due to pump design or just your piping setup.   To stop/minimize that you may need a check valve on the "discharge/output" side.  Do you also have a check valve on the "discharge/output" side or only on the suction/input side?  

 

 

It's actually a constant pressure system there is a large pressure tank (150L) attached as well (at the pump output).

 

I only have a check valve at the output of the pump.

 

rudi

[Artisi]

Are you using or have you tried the NRV that is normally supplied on the inlet side of the Grundfos CH? 

[Artisi]

Why is the valve on the discharge side? 

[luudee]

3 minutes ago, Artisi said:

Are you using or have you tried the NRV that is normally supplied on the inlet side of the Grundfos CH? 

 

I assume NRV stand for "non-return valve", which is basically a check valve, correct?

 

The system was built by a "professional" (used very carefully here, lol) ...

 

I have no idea why the check valve was installed after the pump, or why it would make a difference in the first place ...

 

As I said, the system actually works quite well, except that it eats check valves ... 

 

rudi

 

 

[Pib]

I would just remove that check valve on the discharge side...."normally" they are not needed except with certain setups.  

 

But you should have one on the input/suction side to ensure no backflow to the water source, loss of pump prime, etc.

 

And when they have failed in the past, how did you know they had failed since you can't see into them unless removed and inspected.  What kind of water flow/pump problem occurred to indicate the check valve had failed?

[Artisi]

Remove the NRV from the discharge side, not required, however you need a NRV on the inlet side to maintain  the system pressure, purchase one from Grundfos to suit the pump model. 

In operation the " pressure system"  encompasses everything from the pump side of  the inlet NRV, pump, pressure tank, and pipework -  the reason as to why you don't need a discharge NRV as the whole system in maintained under pressure by the pressure tank. 

 

There should also be an electrical pressure switch to control and maintain the system pressure, to sense a drop in system pressure and run the pump until the pressure is back to the set pressure. This should be fitted somewhere between the pump discharge and the pressure tank. 

The word professional shouldn't be used at all - rank amateur probably doesn't even suit. 

 

Let me know if I can assist further. 

[Artisi]

Forgot to say Non Return Valve is fancy name for check valve. 

[Artisi]

This is the NRV supplied with the Grundfos pump I purchased over 6 years ago. It is fitted on the inlet side of the pump. 

[luudee]

43 minutes ago, Pib said:

I would just remove that check valve on the discharge side...."normally" they are not needed except with certain setups.  

 

But you should have one on the input/suction side to ensure no backflow to the water source, loss of pump prime, etc.

 

And when they have failed in the past, how did you know they had failed since you can't see into them unless removed and inspected.  What kind of water flow/pump problem occurred to indicate the check valve had failed?

 

 

Well, when they fail, the pump constantly runs as it can not build up pressure.

 

It's a constant pressure system. The pressure tank usually holds enough water that the pump only turns on when the system pressure has fallen below a set point.

 

rudi

 

[luudee]

17 minutes ago, Artisi said:

Remove the NRV from the discharge side, not required, however you need a NRV on the inlet side to maintain  the system pressure, purchase one from Grundfos to suit the pump model. 

In operation the " pressure system"  encompasses everything from the pump side of  the inlet NRV, pump, pressure tank, and pipework -  the reason as to why you don't need a discharge NRV as the whole system in maintained under pressure by the pressure tank. 

 

There should also be an electrical pressure switch to control and maintain the system pressure, to sense a drop in system pressure and run the pump until the pressure is back to the set pressure. This should be fitted somewhere between the pump discharge and the pressure tank. 

The word professional shouldn't be used at all - rank amateur probably doesn't even suit. 

 

Let me know if I can assist further. 

 

 

Of course, there is a pressure switch ... 

 

I don't quite understand what you are saying in the first paragraph. This is a well working system, 

except that I can not find a check valve that can handle the backpressure and falls apart ...

 

The Check Vale you are showing in your second post has a plastic "lid" that closes it. This type of

Check Valves will not hold for a day ... 

 

I understand now that placing the Check Valve in front of the pump is the prefered choice.

 

In my case, the inlet of the pump is connected to two 2,000 L water tanks.  The pump is at the

ground level with the tanks, so there is enough pressure from the tanks to prime the pump if needed ...

 

Are there any other reasons to change the location of the Check Valve ? 

 

Will that solve the problem of destruction of the check valve ?

 

Thanks,

rudi

 

[Artisi]

3 minutes ago, luudee said:

 

Well, when they fail, the pump constantly runs as it can not build up pressure.

 

It's a constant pressure system. The pressure tank usually holds enough water that the pump only turns on when the system pressure has fallen below a set point.

 

rudi

 

Of course it won't build up pressure, no NRV, even if it is in  the wrong location. 

The way the valve works under the current set up is, the pump pressurises the valve until it opens allowing some water to pass, the pump pressure drops and the valve slams shut, the pump then builds up pressure again, and the cycle repeats, maybe thousands of times a day - - no wonder the valve fails. 

[janclaes47]

13 minutes ago, luudee said:

Well, when they fail, the pump constantly runs as it can not build up pressure.

So where does the water go, isn't there a tab on the end?

 

If the check valve on the output side needs to close to build up the pressure, then how does that valve open again to let water out?

[Artisi]

It's not a well working system, it "works" but under the destructive manner set out in my previous post. 

[luudee]

Just now, Artisi said:

Of course it won't build up pressure, no NRV, even if it is in  the wrong location. 

The way the valve works under the current set up is, the pump pressurises the valve until it opens allowing some water to pass, the pump pressure drops and the valve slams shut, the pump then builds up pressure again, and the cycle repeats, maybe thousands of times a day - - no wonder the valve fails. 

 

 

Sorry, I don't understand.

 

First of all, the system works - it does build up pressure, etc ... it actually works very

well. Except that I have to replace the Check Vales every couple of months or so ...

 

How is it different if the Valve sits before the pump. Eventually, enough pressure

has been built up and the pump shuts off. The check valve in front of the pump

has to shut. The cycling will NOT be different as if the check valve is after the pump ...

 

Perhaps you are referring to the potential of oscillating, but that is prevented by the

pressure switch, wich has different on and off settings ...

 

rudi

[luudee]

4 minutes ago, janclaes47 said:

So where does the water go, isn't there a tab on the end?

 

If the check valve on the output side needs to close to build up the pressure, then how does that valve open again to let water out?

 

 

Yes, at the end is a tab.

 

No, the check valve closes to hold, the pressure. There is also a pressure tank, that holds about 150L.

 

The Check Valve prevents the water from leaving the system. Once the pressure in the system has

fallen to a certain point, the pump starts up and pressurizes it again.

 

rudi

[janclaes47]

Just now, luudee said:

 

Yes, at the end is a tab.

 

No, the check valve closes to hold, the pressure. There is also a pressure tank, that holds about 150L.

 

The Check Valve prevents the water from leaving the system. Once the pressure in the system has

fallen to a certain point, the pump starts up and pressurizes it again.

 

rudi

 

Honestly I have never seen a system like you explain setup with a check valve at the output.

 

Your check valve should be at the bottom of the pipe in your tank.

[luudee]

5 minutes ago, Artisi said:

It's not a well working system, it "works" but under the destructive manner set out in my previous post. 

 

Again, I do not understand how the location of the Check Valve will reduce the force when it closing.

Whether it sits in front of the pump or after the pump, once the pump stops (at this point it has built

up about 3.5 bar of pressure in the system)  The Check Valve has to absorb the backpressure of those

3.5 bar ? What am  I missing?

 

Thanks,

rudi

 

[wayned]

I've replaced all of the check valves in mu system with on/off valves.  It has nothing to do with the quality of the check valves, but the quality of the water.  My supply has a very high mineral content and the check valves fail in about 9 months, normally in the open position!

[sipi]

We use grundfoss stainless disc check valves in boiler feed water lines but they are expensive. 

Try a boiler parts supplier?

http://www.suppliersof.com/boiler-supplies/th/Samutprakan/74213175

[sipi]

Having just read the thread properly after my morning coffee...

Are you sure it is a non-return valve and not a pressure relief valve?

A relief valve set at 3.5bar on the discharge side makes sense. If you replace it with a swing check valve it won't pressurize the system and the pump will continue to run.

[canuckamuck]

Something really isn't making sense to me here.  Normally in a residential setup you are pumping into a closed system, unless there is a tap open somewhere. So if the system is closed, I cannot see why a check valve would be needed on the output side of a pump. If you can't build up pressure then something is leaking. The pump itself would not allow water to escape on the supply side while it is in operation, so once again no check valve is needed on the output side to maintain pressure. The function of a check valve on the supply side of the pump is to keep water from leaking back through the the pump when the pump is not operating.

It is possible that the OP has a check valve on a bypass back to the supply though. 

A diagram would do wonders for this thread.

[Pib]

9 hours ago, luudee said:

 

Again, I do not understand how the location of the Check Valve will reduce the force when it closing.

Whether it sits in front of the pump or after the pump, once the pump stops (at this point it has built

up about 3.5 bar of pressure in the system)  The Check Valve has to absorb the backpressure of those

3.5 bar ? What am  I missing?

 

Thanks,

rudi

 

A check value on the output side does not absorb the full 3.5 bars.   Since you say the check valve is on the discharge side, the instant the pumps turns off it's not like the pressure on one side of the value (the pump side) and the other side is a 3.5bar differential.  In fact the differential would be very small but enough to close the value.   These values only require about one psi (less than 0.1 bar) to close.

 

As mentioned earlier having the check valve on your discharge side is not needed in a typical setup, but you should have a check valve on the suction side.  Like my Mitsubishi 2.8 bar pump it has check valve "built-in" on the suction side.  But I still have another check valve installed in the input line.

[Artisi]

10 hours ago, luudee said:

 

Again, I do not understand how the location of the Check Valve will reduce the force when it closing.

Whether it sits in front of the pump or after the pump, once the pump stops (at this point it has built

up about 3.5 bar of pressure in the system)  The Check Valve has to absorb the backpressure of those

3.5 bar ? What am  I missing?

 

Thanks,

rudi

 

Rudi, seems as if you are set on maintaining the NRV on the discharge side, your choice but a choice that I and others consider to be incorrect. 

You have said that it works, so do square wheels, although not very well, also if NRV's on the discharge work well, why aren't the thousands of pumps running throughout the world in pressure systems using  this method? 

 

My final comment on the matter is, remove the NRV from the discharge, purchase a NRV that Grundfos supply and fit to the inlet side of the CH pumps - your problems will go away.