small size quick-opening closure
The PWS with its integral locking pin is unscrewed and completely removed. This enables the cap to bepartiallyrotated which separates the seal surfaces givingthe operator a secondary warning if pressure is still presentin the vessel. A further turn of the cap allowsit to bewithdrawn from the hub and swung fully clear using the hinge or davit.
The whole operation can be carried out by one personwithout the need for special tools or wrenches. Totalclosing of the cap is also guaranteed since the lockingmechanism must be fully engaged before the integral pin is relocated and this enables the PWS to be finallyscrewed into its seating.