Flow direction

I like my valve handle to point in the direction of flow when the valve is open, but that's just personal preference. The valve doesn't care, and sometimes in tight installations, the handle just can't turn that direction. This situation invariably causes me to curse profusely and stare at the offending obstacle for several minutes before finally giving over to the inevitable.

A ball vave is symetrical, therefore it doesn't matter, other than for the reasons nicely expressed by the previous answer.

When I saw the post I remembered buying a ball valve with an arrow on it. It is installed in an awkward place but I had a look at it and it does have an arrow.

Habits Die Hard:

• With the Body Casting mould maker
• With the Body Forging Die Maker
• With the Plumber( W'ere is theflipping arrow?)

Thats what I decided when Installing the thing. The arrow is pointing in the wrong direction and it is working ok.

The arrow direction won't affect the operation of the valve, only its behaviour if it leaks.

I remember a similar situation working with hydrogen peroxide, which can decompose releasing gas, causing high pressure in the trapped volume in the valve (when closed). So valves were spec'd to have a drilled ball to relieve. I assume the hole would be best pointing downstream when valve open, and this would indicate a preferred flow direction.

Cheers.....Codey

"I assume the hole would be best pointing downstream when valve open, and this would indicate a preferred flow direction."

I agree that the hole should be pointing downstream, but only if that is the higher pressure side when the valve is closed, which is normaly but not always the case. By facing the hole to the high pressure side, the ball will be pressed against the seal at the lower pressure side when closed.

This is problematic as an arrow indicates the flow direction not the low or high pressure side, so care has to taken with valves relieved in this way.

I have about 100 of them in use on the air lines in the plant. Most point when open in the opposite direction of the air flow. I had them installed that way as they are drops to equipment and it is easier with a pole attachment I have to pull down on them to close them. If I had to push up then the line would move with force. I have never seen one that the flow was directional. If the flow is directional the device is usually marked.

I like my valve handle to point in the direction of flow when the valve is open, but that's just personal preference.

I agree with him.

Many good replys. Another consideration is the safety of the quarter turn handle. You may not want the valve to be opened incidentally/accidently by leaning or bumping against it. A method to guard against this is using BVs with a round or elliptical handle. Theses, too, have a draw back in that they are difficult to turn with wet or slippery hands or gloves.

Happy plumbing!

The King

It can depend on the size, flow, pressure, chemistry, erosion . . . . so check with the manufacturer if this is an engineered valve. Ball valves in my world are for pipeline duty at 20 - 50 inch size up to 2500 psig and one million barrels of flow per day (48"). When a ball valve fails, the failure will not be symmetrical which indicates that direction of flow does different things to leading edges, and as such, ball valve manufacturers may provide counter measures in design due to flow direction.

For all projects of oil & gas, I didn't used a ball valve with a flow direction.