You can expect to pay about 30 more for a bi directional knife gate valve.
Bidirectional vs unidirectional knife gate valve.
Bi directional knife gate valves will seat on either side of the gate and operate with back pressures providing adequate water tightness and has a tendency of avoiding any build up of solids that could prevent the valve from closing.
Knife gate valve seat options include metal seat and resilient seat which can be offered as unidirectional and bidirectional.
The series 740 bidirectional knife gate valve provides repeatable bidirectional shutoff in a rugged single piece cast body featuring a replaceable steel reinforced elastomer seat for enhanced sealing the bray series 740 gate valve is easily automated for on off applications.
The series 940 unidirectional knife gate valve features a single piece cast body design offers rugged performance in applications ranging from general purpose to severe media handling available with integral metal or replaceable soft seat the series 940 gate valve is easily automated for on off applications.
Mvs knife gate valve can be operated through hand wheel rising stem and non rising stem chain wheel lever bevel gear electric actuator pneumatic cylinder and hydraulic actuator.
Unidirectional knife gate valves seat on just one side.
Designed for easy quick conversion between manual and pneumatic actuation.
The bray series 752 bidirectional knife gate valve features a robust steel reinforced perimeter seat which provides bidirectional zero leakage shutoff.
The replaceable steel reinforced perimeter seat is mechanically retained between both halves of the two piece bolted body for unsurpassed performance in the most demanding applications.
The biggest difference is price.