FAQ

1. What is the displacement requirement of the instrument selected?
Regardless of the type of instrument, the displacement capability of the diaphragm seal must exceed the displacement requirement of the instrument. Vacuum applications or instruments that are to be in compound service (atmospheric and less than atmospheric pressure) should be reviewed with Winters.

2. What is the expected accuracy of this diaphragm seal and instrument?
Knowing what is expected from the instrument is essential in defining the specification. The accuracy is typically stated as the greatest inaccuracy allowable as a percentage of full scale indication. The addition of the diaphragm seal may have a compounding effect to the accuracy of the indication. Try to optimize the performance relative to the cost impact.

3. What is the range of process and ambient temperatures?
Choose a fill fluid that will be well within the operating temperature range to avoid vapourizing the fluid and minimize errors. Winters can provide the thermal coefficient of expansion for various fill fluids. Care should be taken in selecting compatible fill fluids when the process media is considered a strong oxidizer or is reactive with hydrocarbon-based silicones (i.e. oxygen, chlorine, fluorine).

4. What type of piping system is the diaphragm seal to be mounted?
Industrial piping systems can require flanged off-line, threaded off-line, and many styles of inline process connections. Care should be taken in selecting a diaphragm seal assembly that will maintain or exceed the piping systems maximum working pressure. Sanitary piping systems require specialized flange configurations and surface finishes. There are also many non-standard or custom designed configurations available.

5. What is a compatible material of construction?
A wide variety of exotic metal alloys and non-metallics is available. Attention should be given to the reduced pressure and temperature limitations of non-metallics. When in doubt, look at the material of the existing piping system or storage vessel. Like materials are usually available as diaphragm seal materials.

6. How is the diaphragm seal mounted to the instrument?
The diaphragm seal can be mounted directly to the instrument or by utilizing capillary lines to place the instrument further away from the process containment. Long capillary lines (in excess of 20’) will contribute to inaccuracies and slow response.

7. How and who is going to fill the instrument and diaphragm seal?
Knowledge of high-vacuum technology and filling techniques is imperative to the successful application of a diaphragm seal. An assembly that is 99% filled will never provide acceptable performance. Winters sells diaphragm seals and instrumentation that ship to customers completely filled. Winters also offers fluid filling service.

8. What are the common fill fluids for Winters diaphragm seals?
Glycerin-water is the standard fill fluid used in our diaphragm seals. Silicone fill fluid is used for higher temperature applications. When oxidizers are present, Halocarbon®, Fluorolube® and Krytox must be specified. Process and ambient temperatures, pressure and compatibility with the media must be considered when specifying non-standard fill fluids.







Halocarbon® is a registered trademark of the Halocarbon Products Corporation
Fluorolube® is a registered trademark of Hooker Chemical Co.
Krytox® is a registered trademark of DuPont Corporation