Diaphragm seals
Diaphragm seal consists of an elastic element that
insulates the process fluid from the sensing element,
transmitting pressure through the compression of a
liquid in a separation chamber.
It is necessary to adapt this device where there are
particular physical and chemical characteristics
incompatible with the sensing element. This way the
instrument is no more subject to drawbacks caused
by particularly aggressive fluids or by highly viscous,
crystallizable or solidifiable process fluid.
The diaphragm seal is an integral part of the
instrument, so there is no possibility of
disassembling.
Diaphragm seals shown below are suitable born for
SP 300 and SP 2000 series (Bourdon tube pressure
gauges), for DP series (differential pressure gauges),
for TR series (pressure gauges with integrated
trasmitter) and SE series (transmitters or pressure
switches).
TECNICAL FEATURES
• Mounting
- direct; (identification R)
- remote by flexible capillary with 8 meters maximum lenght (5 meters for differential pressure gauges). (identification S followed by the number indicating the capillary length in meters)
note: the remote mounting requires seal and pressure gauge set at the same level to avoid false calibration.
• Capillary material
- AISI 304 stainless steel with flexible armour;
- AISI 304 stainless steel with flexible armour and PVC protection (option V79).
• Element (see special materials)
o diaphragm:
- AISI 31L st. st.
- AISI 316L st. st. with P.T.F.E. coating;
- special materials (Monel 400, Hastelloy C276 titanium, tantalum).
o bellows:
- AISI 304 stainless steel (FP 344).
note: for differential pressure gauges the diaphragm is of bigger diameter.
• Body material (see specific models)
o upper part (where scheduled):
- AISI 304 stainless steel.
o pressure connection:
- AISI 316L stainless steel;
- AISI 316L stainless steel with P.T.F.E. coating;
- galvanized carbon steel (FP344);
- special materials (Monel 400, Hastelloy C276, titanium, tantalum).
• Pressure connection (see specific models)
- threaded;
- flanged;
- sanitary.
• Diaphragm position (see specific models)
- facing;
- back side.
• Filling fluid (see specific models)
- silicone fluid;
- diathermic fluid;
- food compatible fluid;
- fluoride fluid (for oxygen services).
• Working pressure
note: when a diaphragm seal is fitted to a differential pressure gauge, lowest working pressure is 60 mbar, the higher is the one of the specific model.
• Accuracy class
- see table FP 1 at page FP03
• Operating temperature (see specific models)
- +10 ÷ +70 °C, standard;
- -10 ÷ +10 °C, on request; (identification T1)
- -30 ÷ -10 °C, on request; (identification T2)
- +70 ÷ +150 °C, on request; (identification T3)
- +150 ÷ +300 °C, on request. (identification T4)
note1: calibration is made according to the customer requested control temperature; otherwise it is made at ambient temperature included between +10 and +25°C.
note2: if the diaphragm seal is fitted to a differential pressure gauge, operating temperature value is included between -20 and +120 °C.
note3: P.T.F.E. coated seals operating temperature value is included between -20 and +120 °C.
| 
