The SSV is an automatic wellhead valve which shuts off the flowstream upon loss of supply pressure. API 6A specifies that the SSV must be assembled as the second valve in the wellhead flowstream. Neeco offers an SSV with a diaphragm pneumatic actuation that pneumatically powers the gate valve to open and close. All series of Neeco diaphragm actuators are similar in simplicity of design giving customers the ability to interchange repair parts. This series of actuators offers the user several options depending on the gate valve size and pressure rating.