Diaphragm Seal construction

The most common instrument mounting configurations are a DIRECT mount and a REMOTE mount pressure instrument to the Diaphragm Seal System. Diaphragms are mounted in different variations to the pressure instruments in order to meet the specific situation in the plant. Multiple variations are possible in each situation. The challenge is to select the variant that has the most advantages in the light of accuracy, accessibility of the instruments, and maintenance.

Remote mounting construction

Remote mounting is a construction where the pressure instrument is mounted by means of a capillary to the diaphragm seal. This type of mounting is common when installing 2 diaphragm seals to a DP pressure transmitter. The use of capillary lines allows that the transmitter can be positioned in the best place to avoid excessive mounting effects.

With GP transmitters it is used when the transmitter needs to be mounted away from environmental conditions or process conditions like temperature. The flexible way of mounting allows different positioning. The capillary is standard with AISI 304 armor around the capillary line. Optionally the armor can be AISI 316. Protective covers in black or white color can be applied as well. For ATEX environments the capillary can be covered with a flame retardant cover with ATEX conformity.

Direct mount construction

Direct mounted pressure instruments are mostly used in GP pressure instrument installation. For example pressure gauges mounted to threaded diaphragm seals are commonly direct mounted. GP pressure transmitters can be mounted direct to the diaphragm seal as well The advantage is that the fill volume is kept as minimum as possible. This reduces the ambient temperature effect and compressibility of the fill fluid.

When having DP transmitters a combination of direct mount and remote mount can be selected. However this is easier with installation there are downsides as well. One of them is the difference in fill fluid volume that can lead to a higher static pressure effect.

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