Liquid filled pressure gauges refer to the internals of the gauge being submerged within glycerin liquid. The glycerin provides a few advantages such as protecting the internals from corrosion. The glycerin fill also helps reduce the effect of fluid and line pulsation from moving pointer, making it easier to read the gauge accurately. Lastly there's a lubrication aspect to glycerin fill which helps keep the mechanism (often consisting of gears and cogs) working smoothly. We can also use silicon for as a fill liquid as some applications might be sensitive to the potential for glycerin contamination in the event of catastrophic gauge failure.
Most liquid filled gauges can be supplied "dry", enabling the customer to fill with their own liquid or perhaps simply use them without fill. Thus the primary pressure gauge design difference between liquid filled pressure gauges and inexpensive utility style gauges is the way the case is sealed; and of course, the liquid fill.
It cannot be assumed that the accuracy of a liquid filled gauge is increased just because it is fillable, however, generally speaking, as the complexity of the gauge design increases, so does the potential for improvement of the internal components and accuracy. Likewise, there are highly accurate non-fillable dry gauges we offer for applications for which a liquid fill is a concern. A good description of your application requirements will enable us to select the most appropriate gauge for your application.
View/Download the Glycerin Filled Pressure Gauges catalog section.