Modern service manifolds incorporate additional hand valves, connections for a vacuum pump, and a liquid-indicating sight glass. Some feature Schraeder valves in addition to the normal hand valves on the manifold. These additional valves make it possible to perform various operations without the necessity for removal of the manifold or hoses.
The Schrader valve is similar to that used in cycle or car tyres (Figure 7). The fitting into a system can vary: it may be brazed in, screwed into a component or supplied as a flare connector.
When connection is made to this type of valve it is necessary for the service hose to include a quick release adaptor. This depresses the valve stem and allows passage of refrigerant into the hose.