Check Valve Flow Direction: Arrow and Mounting Position
Check Valve Installation Guide
A check valve’s flow arrow points in the intended direction of forward flow. Match it to the normal flow through the pipe. Then check the permitted mounting position: an arrow pointing the right way does not, by itself, confirm that the valve can work in that position. [1][2]
Make two separate checks
1. Which way should the fluid pass? Identify upstream and downstream from the piping arrangement. Compare that direction with the arrow on the actual valve body. A check valve opens for forward flow and closes against reverse flow; it is not an unrestricted fitting that can simply be turned either way. [1]
2. Is this mounting position allowed? Record whether the pipe is horizontal, vertical with upward flow, or vertical with downward flow. Look up the installation instructions for the exact valve and configuration. Do not stop at a general label such as “swing check” or “spring check.” [1][2]
Why the exact configuration matters
These documented examples show why a single orientation rule is unreliable.
| Documented valve/configuration | Mounting rule in its manufacturer’s documentation |
|---|---|
| C&C CVA Series swing check | Horizontal: cover upright, arrow with flow. Vertical: upward flow only; downward flow is not permitted. |
| Spirax Sarco DCV6 with a spring | Can be installed in any plane; the flow arrow must still match fluid flow. |
| Spirax Sarco DCV6 without a spring | Must be installed in a vertical line with bottom-to-top flow. |
Sources: C&C CVA manual, section 4 [1]; Spirax Sarco DCV6 technical sheet, page 5 [2]; TLV CK Series product information [3].
The DCV6 example is particularly useful: the series name alone is insufficient. The version supplied without a spring has a different permitted orientation. Treat the table as a demonstration of what to verify, not permission to apply these rules to another manufacturer’s valve.
If the arrow is missing or unclear
Use the valve identification and manufacturer drawing to establish the inlet and outlet before installation. Record the model, size and any configuration marking; keep a photograph of the nameplate and body. If you cannot establish which documentation applies, ask the manufacturer to confirm the direction and position. Do not infer them from body shape alone.
If the arrow is correct but there is still no flow
Direction is only one check. In the C&C CVA troubleshooting table, incorrect placement is a listed cause of no flow. The relevant manufacturer’s operating requirements must also be checked: opening differential pressure and the actual spring configuration can matter. TLV, for example, lists opening differential pressure as a CK Series selection characteristic. [1][3]
Before signing off the direction and mounting-position check, write down four items together: normal flow direction, body-arrow direction, installed position, and the document confirming that position for this configuration. This gives the next person something concrete to verify.