Oil sight glass with reflector

The conical thread of the oil sight glasses GN 743.7 makes a metallic seal possible. When tightening the conical external thread R it blocks itself with the appropriate cylindrical internal thread Rp. With the datum plane a the R-external thread has the same thread diameter as the Rp-internal thread, so that it can be screwed in by hand. The strong tightening by means of a tool increases the length of engagement and seals the screw connection. Additionally a sealant (hemp or teflon band) is usually used. The R-thread is „roughened“, so that the sealant does not shift when screwing in. Oil sight glasses GN 743.7 can also be used on pressurised tanks. Tests regarding maximum pressure are available.