WIKA 851 - Manual (Page 13)

WIKA operating instructions magnetic snap-action contact model 821 13
GB
Correct sealing of pressure gauge connections with parallel threads 
must be made using suitable sealing rings, sealing washers or WIKA
profile seals. The sealing of tapered threads (e.g. NPT threads) is made
by providing the thread , with additional sealing material such as, for
example, PTFE tape (EN 837-2).
The torque depends on the seal used. Connecting the gauge using
a clamp socket or a union nut is recommended, so that it is easier to
orientate the gauge correctly. When a blow-out device is fitted to a
pressure gauge, it must be protected against being blocked by debris
and dirt.
2003325.03 03/2011 GB/D/F/E
Spanner flats Sealing in the
thread 
Sealing face 
Installation with
open-ended spanner
8. Commissioning, operation
8. Commissioning, operation
8.1 Mechanical connection
In accordance with the general technical regulations for pressure
gauges (e.g. EN 837-2 "Selection and installation recommendations for
pressure gauges" and/or EN 13190 "Dial indicating thermometers").
When screwing gauges in, the force required for this must not be
applied through the case or the cable terminal box, but rather through
the spanner flats (using a suitable tool) provided for this purpose on the
square shaft of standard connections.