Globe valves (Fig. 7.73) should not be used unless particular attention has been paid to hygienic design. They incorporate packed glands making cleaning extremely difficult and, furthermore, their flow characteristics are often unsatisfactory.
Membrane Sampling Valves
Sampling valves are used to take small samples of the fluid inside a tank or pipe. The sampling valve as shown in Fig. 7.74 is designed to be cleaned and sterilized during production, once the sample has been taken. The V-shaped valve has an outlet port for the sampled fluid and an inlet port for chemical cleaning (CIP) and/or steam cleaning (SIP). After flushing the fast draining valve chamber with cleaning solution, it can be rinsed and subsequently disinfected or steam sterilized if required. Via the outlet port, cleaning/disinfectant solutions and condensate are allowed to drain from the valve body.
In some occasions, the plunger is spring-loaded. On release of the plunger, the spring pressure then moves the plunger against the valve seat, hence closing the sample valve opening in front of the plunger.