Diaphragm seals (also called chemical seals, instrument isolators, and gauge protectors) are isolation devices used to separate pressure instruments from the process media, while allowing the instruments to sense the process pressure. A diaphragm, or bladder, together with a fill fluid, transmits pressure from the process medium to the pressure element assembly of the instrument. Diaphragm seals may be attached directly to the instrument, or remotely, using a capillary line. These devices are intended to keep the process medium out of the pressure element assembly and to prevent damage from corrosion or clogging.  Diaphragm seals are also used to maintain the sanitary requirements of the process medium and to reduce the process temperature to which the pressure element is exposed. Diaphragm seals function using a flexible diaphragm that is attached between the upper and lower housing of the seal. The upper housing is filled with a fluid and attached to the pressure instrument. The lower housing is in contact with the process medium and has the connection to the process system. The process media pressure is transmitted via the diaphragm to the fill fluid in the upper housing and subsequently to the pressure instrument.