In order to prevent live steam from
entering the Bourdon tube, a siphon filled with water should
be installed between the gauge and the process line.
Siphons can be supplied with ratings up to 4,000 psi. If
freezing of the condensate in the loop of the siphon is a possibility,
a diaphragm seal should be used to isolate the gauge
from the process steam. Siphons should also be used whenever
condensing, hot vapors (not just steam) are present.
Super heated steam should have enough piping or capillary
line ahead of the siphon to maintain liquid water in the
siphon loop.