What key aspect does a pigtail siphon provide in boiler instrumentation?

A pigtail siphon plays a crucial role in boiler instrumentation by protecting the gauge from pressure fluctuations. This device is essentially a loop of piping that contains water, which serves to separate the pressure gauge from the direct effects of steam pressure.

When steam passes through the siphon, the water inside acts as a buffer. This buffer helps to dampen the effects of temperature changes and rapid fluctuations in pressure that could otherwise lead to inaccurate readings or even damage to the gauge itself. By maintaining a more stable environment for the gauge, the pigtail siphon ensures that the pressure readings are reliable and reflective of the true system conditions.

Other choices focus on different aspects. For instance, while preventing thermal stress and increasing efficiency are important in boiler operation, they are not the primary functions of a pigtail siphon. Similarly, measuring discharge pressure falls more under the function of pressure gauges themselves rather than the protective role that the siphon provides. Therefore, the primary benefit of a pigtail siphon in boiler instrumentation is its ability to shield the gauge from potentially damaging pressure fluctuations.