Pressure Gauges: Service as a gauge for air, water, steam, oil or sea water and any liquid or gases which are not corrosive to brass. Brass case, friction fit beaded ring and phosphor bronze Bourdon tube. Compound Gauges: For installations where it is necessary to read both pressure and vacuum on one side. Brass case and friction fit beaded ring. Phosphor bronze Bourdon tube. Vacuum Gauges: For vacuum reading. Brass case, friction fit beaded ring and phosphor bronze Bourdon tube. Due to the great variety of casing, fitting connections, etc. in above gauges, please refer to the following illustrations and the “Guide of how to order” when ordering. The thread connection is the same as pipe straight threads (PF) which are of the “B.S.P.” (British Standard Pipe Threads).