Screw thread gauges

The valves and screw threads of cylinders and regulators should never be greased since this may lead to an explosion. If a cylinder has a very stiff spindle valve or if the screw threads are damaged, it should be returned to the suppliers for replacement. Similarly, defective regulators and pressure gauges should never be used. 

For checking internal threads, e.g. nuts, a double-ended screw plug gauge. Fig. 5.13 may be used. This gauge has a GO end which checks... 

Nowadays there are two main types of stationary mercury electrodes. One type consists of a capillary joint to a displacement vessel into which a micrometer gauge rod is screwed. The drop size is determined by the screw thread of the micrometer and the rotation [6]. The other type uses a microvalve (needle valve or flat valve) instead of the micrometer rod to determine the drop size by the time the valve is opened (usually a few msec). 

Cleaning of the mixer seems to be easy, however this is must done quite meticulously. Almost all parts can be demounted and be cleaned separately. In any case extra attention is necessary for several connection points, the thermometer, the inner side of the pressure gauge and the inner side because they are provided with a rubber ring or contain a difficult cleanable screw thread. The apparatus does not contain its own drain, therefore the cleaning with soap water and the rinsing of the inner side requires a considerable amount of time. 

After completion of the fluorination, the liquid CIF3 is poured from the Dry Ice-cooled trap into a steel cylinder again cooled with Dry Ice (without acetone ) (use a good hood, protective goggles and rubber gloves) and a threaded shut-off valve is immediately screwed on. When the steel cylinder has warmed up to room temperature, an iron manometer and an additional valve are screwed on and the contents of the cylinder are allowed to escape imtil a gauge pressure of 1.2 atm. is reached. The GIF, Gig and Fg are thereby removed. 

Pressure measurement for piping and vessels is achieved by the installation of dial indicators or by distributed control systems. The piping and vessels are tapped at the required location and furnished with a 3/4-in threaded or flanged conneaion and a block valve. Tbe dial indicator is screwed into the block ralve if a remote readout system is required, the valve becomes the sensing connection. Like the thermocouple, the dial can be either fixed or swivel-headed to fecilitate readout. A dual local indicator and transmitter s) em needs only one tapping point. Exhibit 14-9 depicts a typical pressure gauge and a dual-pressure system hookup. 

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