The type of liquid used to fill the gauge varies with the application. Although pure glycerine provides the best performance in most applications, each has its own requirements. Guidelines to help ensure that a fluid is properly matched to an application are:
 

1. If icing is a problem, use gauges filled with silicone oil or other comparable liquids - they have low viscosities even at -60°C.
    
2. If the system has electric accessories, such as contacts, use insulating oils.
    
3. If extreme temperature fluctuations are expected, use silicone oils. The higher the liquid viscosity, the greater its dampening capacity. The reason for this is that dampening changes in proportion to the temperature-dependent viscosity of the filling liquid. The suitable degree of dampening depends on the operating requirements the gauge must meet, such as pointer response time, pressure extremes, vibration and changes in pressure. WIKA can recommend specific liquids to suit problem applications.
    

Liquid-filled pressure gauges provide a number of advantages:
 

1. The liquid absorbs vibration and pressure spikes.
    
2. The dampening action of the liquid enables the operator to take reading during conditions of rapid dynamic loading and vibration.
    
3. The liquid lubricates all moving elements, dramatically reducing wear in the movement.
    
4. Because most liquid-filled gauges are filled with non-aqueous liquid and hermetically sealed, they perform in corrosive environments and are immune to moisture penetration and icing.