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| Class 251 | VALVES AND VALVE ACTUATION |
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![[List of Pre Grant Publications for class 251 subclass 1.1]](../as.gif) | ![[List of Patents for class 251 subclass 1.1]](../ps.gif) | 1.1 | BLOW-OUT PREVENTERS (I.E., COOPERATING SEGMENTS OF ANNULUS) |
| | 3 | PATTERN TRACER CONTROLLED ACTUATOR |
| | 4 | TUBE COMPRESSORS |
| | 5 |  Fluid pressure actuated |
| | 6 | Roller tube contacting element |
| | 7 | Perpendicularly reciprocating tube contacting element |
| | 9 | Pivoting tube contacting element |
| | 11 | HEAT OR BUOYANCY MOTOR ACTUATED |
| | 12 | FLUID ACTUATED OR RETARDED |
| | 14 | Fluid and non-fluid actuators |
| | 15 | Compulsory cut-off after flow period |
| | 16 |  Serial main line cut-off and manual valves (e.g., hydraulic "fuses") |
| | 19 | Auxiliary pilot valve overrides a first pilot valve |
| | 20 | Forced return of actuator to cut-off position |
| | 21 | Actuator connection released on opening of cut-off valve |
| | 22 | Control fluid released into closed build-up chamber |
| | 23 | Dashpot interconnects actuator and valve |
| | 24 | Venturi or line flow effect assisted |
| | 25 | Pilot or servo type motor |
| | 26 | Alternative pressure sources or pilot valve |
| | 27 | Servo failure responsive control of main valve |
| | 28 | Fluid actuated pilot valve |
| | 30.01 | Electrically actuated pilot valve |
| | 31 | Double or oppositely acting motor units |
| | 32 | Latched pilot valve |
| | 33 | Choked pressure type servo motor |
| | 34 |  With reverse flow prevenging (nonsiphoning) |
| | 35 | Variable choke passage according to valve position |
| | 36 | With separate dashpot or choked fluid retarding chamber |
| | 37 | With choke or restrictor in main line |
| | 38 | Pilot valve seated in motor or valve element |
| | 41 | Remote pilot valve actuation |
| | 42 | Adjustable opening limit for main valve |
| | 43 | Main valve biased open by line pressure |
| | 47 | With separate dashpot or choked fluid retarder |
| | 48 | Dashpot or fluid controlled retarder or timer |
| | 49 | Latch or trip releasing |
| | 50 | Line pressure connected dashpot or choke chamber |
| | 53 | Line connected open accumulating chamber |
| | 54 | Closed fluid circuit dashpot or choke chamber |
| | 55 | With choke by-pass or relief means |
| | 56 | Plural operations (e.g., lifting and rotating rotary valve) |
| | 57 | Fluid link or column actuator |
| | 58 | With mechanical movement between actuator and valve |
| | 59 | Rotary or oscillatory motor |
| | 60 | With adjustable limit stop for actuator |
| | 61 | Flexible wall expansible chamber reciprocating valve actuator |
| | 62 | Piston type expansible chamber reciprocating valve actuator |
| | 64 | WITH NON-FLUID RETARDER |
| | 65 | PERMANENT OR CONSTANTLY ENERGIZED MAGNET ACTUATOR |
| | 66 | BIASED TRIP |
| | 67 | With second diverse control |
| | 68 | Electrical trip actuation |
| | 72 | Weight biased trip |
| | 73 | Fluid pressure trip actuation |
| | 74 | Mechanical movement trip actuation |
| | 75 | WITH SNAP ACTION |
| | 76 | IMPACT TYPE ACTUATOR |
| | 77 | LOST MOTION BETWEEN ACTUATOR AND VALVE |
| | 84 | VALVE HEAD MOVABLY CONNECTED FOR ACCOMMODATION TO SEAT |
| | 85 | With yieldable connection |
| | 86 | With universal connection |
| | 87 | With single plane swing pivoted connection |
| | 88 | Rotatable only |
| | 89 | WITH MEANS FOR BLOCKING OR DISABLING ACTUATOR |
