Single Union Ball Valve - Direction of Flow [Archive]

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milkman55

11/14/2009, 03:38 PM

I am plumbing my new tank and could not find any direction of flow on the single union ball valves I got from Flex PVC. Does it matter if the union joint is upstream or downstream from the pump flow direction?

I am putting a ball valve on either side of my external Pan World pump so I can take it out of service as needed. If direction can be either way, probably makes sense to put the unions next to the pump joints, so the ball valves stay on the piping when the pump is removed?

I also am putting a gate valve downsteam from the ball valve to regulate flow. These single union ball valves are just for servicing.

Jeff

11/14/2009, 03:57 PM

It doesnt matter, it isnt a one way valve.

milkman55

11/14/2009, 04:59 PM

Thanks Jeff, thats what I thought, but better one stupid question than needing to purchase all my PVC material over again.

der_wille_zur_macht

11/14/2009, 06:33 PM

Clearly you want to orient it so that the ball valve "stays with" the wet part of the plumbing when you disassemble the union.

In other words, let's assume you were using that SUBV between your sump and your sump pump. You'd want the union on the pump side of the valve, so you could use the valve to shut off water and disassemble the union to remove the pump from the system for maintenance.

Similarly, if the SUBV was between the pump and the display tank, you'd want the union on the pump side, for the same reason.

milkman55

11/14/2009, 07:18 PM

Thanks, it all makes sense to me now.

NanoReefWanabe

11/14/2009, 07:22 PM

yeah the union should always be on the pump side

james3370

11/15/2009, 11:13 AM

yeah....i learned this by personal experience LOL

i was dry fitting & posted some pics. melev noticed my mistake & pointed it out. i ended up having to break out the hacksaw since i had already glued it

http://img.photobucket.com/albums/v501/james3370/smileys/doh.gif

BeanAnimal

11/15/2009, 01:07 PM

In a similar fashion... many TRUE UNION valves have a fixed end and a loose end. You want the fixed end towards the side that needs to hold water during maintenance. The lose end allows the ball to replaced during dry maintenance.