Should diaphragm pressure transmitters use gaskets without an inner ring?
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Our company is carrying out construction work on a certain project, and the design calls for the use of metal wound gaskets with both an inner ring and an outer ring for the diaphragm-type pressure transmitters. However, it was discovered at the start of work that the inner ring was pressing against the diaphragm, which resulted in poor performance of the transmitters; in some cases, the diaphragms even leaked oil (due to compression). Should we instead use gaskets without an inner ring?
It definitely won’t work. If the diaphragm gets damaged or deformed, even if it’s just a slight dent, it needs to be sent back to the factory for repair. As for oil leakage, that’s even worse – the silicone oil used serves to transmit pressure, and it’s adjusted properly before the product leaves the factory. Once there’s oil leakage, the device is basically unusable; it has to be sent back to the factory for repair
Under such operating conditions, the diaphragm is already damaged, affecting the measurement or even making it impossible to take measurements. The washer must not cover the diaphragm, and the diaphragm must not be compressed or deformed
The inner diameter of the inner ring gasket will never be smaller than the inner diameter of the flange opening; therefore, the fact that the diaphragm is compressed to 100% is a matter of construction quality. That said, it is indeed difficult to detect when the inner ring gasket is misaligned; moreover, the inner diameter opening of outer rings or gaskets without rings is often larger than that of the flange opening, making them more convenient for use with flat flanges.
Yes, gaskets without an inner ring should be used; for various reasons, gaskets with an inner ring cannot ensure that products from all manufacturers will function properly (theoretically it should work, but in practice it doesn’t).
Without an inner ring, leakage can still occur from the gasket material; it’s necessary to choose a suitable gasket
Gaskets can be provided by the transmitter manufacturer during delivery, which ensures that there are no issues with dimensions and specifications. Pay attention to the installation method during setup, and basically no problems will arise
It is not suitable to use inner and outer metal wound gaskets for diaphragm pressure transmitters, as the force applied will cause the gaskets to deform, which may damage or compress the diaphragm and lead to problems with the transmitter.
It’s not meant to criticize Heiheng River; the design of that flange diaphragm doesn’t allow the use of ordinary gaskets, as this results in inaccurate readings as soon as a gauge is connected. Lao Luo doesn’t have this problem. Upon close comparison, it can be seen that Yokogawa’s diaphragm design does not feature a flat flange; although it is called a flat flange, there is still a protruding section, which means that the inner diameter of the gasket must be relatively large.
Custom gaskets are used, as the size of standard gaskets does not match that of the diaphragm seal surfaces.
The gasket manufacturer can be asked to cut off a portion of the inner ring of the gasket, so that it no longer presses on the diaphragm; this ensures the quality of the gasket.