|  | F |
SECTION F — MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING

ENGINEERING IN GENERAL

|  | F16 |
ENGINEERING ELEMENTS AND. UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS

|  | F16K |
VALVES; TAPS; COCKS; ACTUATING-FLOATS

|  | F16K 1/00 - F16K 13/00 |
Constructional types (check valves Fulltext... Hierarchy... Expanded...F16K 15/00)

|  | F16K 1/00 |
Lift valves, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces (diaphragm valves Fulltext... Hierarchy... Expanded...F16K 7/00)

|  | F16K 1/02 |
· | with screw-spindle (Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...F16K 1/12-F16K 1/28 take precedence; actuating mechanisms with screw-spindles Fulltext... Hierarchy... Expanded...F16K 31/50)

|  | F16K 1/04 |
· · | with a cut-off member rigid with the spindle, e.g. main valves

|  | F16K 1/06 |
· · | Special arrangements for improving the flow, e.g. special shape of passages or casings

|  | F16K 1/08 |
· · · | in which the spindle is perpendicular to the general direction of flow

|  | F16K 1/10 |
· · · | in which the spindle is inclined to the general direction of flow

|  | F16K 1/12 |
· | with streamlined valve member around which the fluid flows when the valve is opened

|  | F16K 1/14 |
· | with ball-shaped valve members (check valves Fulltext... Hierarchy... Expanded...F16K 15/04)

|  | F16K 1/16 |
· | with pivoted closure members

|  | F16K 1/18 |
· · | with pivoted discs or flaps

|  | F16K 1/20 |
· · · | with axis of rotation arranged externally of valve member

|  | F16K 1/22 |
· · · | with axis of rotation crossing the valve member, e.g. butterfly valves

|  | F16K 1/226 |
· · · · | Shaping or arrangement of the sealing

|  | F16K 1/228 |
· · · · · | Movable sealing bodies

|  | F16K 1/24 |
· | with valve members that, on opening of the valve, are initially lifted from the seat and next are turned around an axis parallel to the seat

|  | F16K 1/26 |
· · | Shape or arrangement of the sealing

|  | F16K 1/28 |
· · · | Movable sealing bodies

|  | F16K 1/30 |
· | specially adapted for pressure containers

|  | F16K 1/32 |
· | Details (details of more general applicability Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...F16K 25/00-F16K 51/00)

|  | F16K 1/34 |
· · | Cutting-off parts, e.g. valve members, seats (Fulltext... Hierarchy... Expanded...F16K 1/06, Fulltext... Hierarchy... Expanded...F16K 1/12, Fulltext... Hierarchy... Expanded...F16K 1/14, Fulltext... Hierarchy... Expanded...F16K 1/26 take precedence)

|  | F16K 1/36 |
· · · | Valve members (for double-seat valves Fulltext... Hierarchy... Expanded...F16K 1/44)

|  | F16K 1/38 |
· · · · | of conical shape

|  | F16K 1/40 |
· · · · | of helical shape

|  | F16K 1/42 |
· · · | Valve seats (for double-seat valves Fulltext... Hierarchy... Expanded...F16K 1/44)

|  | F16K 1/44 |
· · · | Details of seats or valve members of double-seat valves

|  | F16K 1/46 |
· · · | Attachment of sealing rings

|  | F16K 1/48 |
· · | Attaching valve members to screw-spindles

|  | F16K 1/50 |
· · | Preventing rotation of valve members

|  | F16K 1/52 |
· · | Means for additional adjustment of the rate of flow

|  | F16K 1/54 |
· · | Arrangements for modifying the way in which the rate of flow varies during the actuation of the valve

|  | F16K 3/00 |
Gate valves or sliding valves, i.e. cutt-off apparatus with closing members having a sliding movement along the seat for opening and closing (Fulltext... Hierarchy... Expanded...F16K 5/00 takes precedence; in barrages or weirs Fulltext... Hierarchy... Expanded...E02B 8/04)

|  | F16K 3/02 |
· | with flat sealing faces; Packings therefor

|  | F16K 3/03 |
· · | with a closure member in the form of an iris-diaphragm

|  | F16K 3/04 |
· · | with pivoted closure members

|  | F16K 3/06 |
· · · | in the form of closure plates arranged between supply and discharge passages (Fulltext... Hierarchy... Expanded...F16K 3/10 takes precedence)

|  | F16K 3/08 |
· · · · | with circular closure plates rotatable around their centres

|  | F16K 3/10 |
· · · | with special arrangements for separating the sealing faces or for pressing them together

|  | F16K 3/12 |
· · | with wedge-shaped arrangements of sealing faces

|  | F16K 3/14 |
· · · | with special arrangements for separating the sealing faces or for pressing them together

|  | F16K 3/16 |
· · | with special arrangements for separating the sealing faces or for pressing them together (Fulltext... Hierarchy... Expanded...F16K 3/10, Fulltext... Hierarchy... Expanded...F16K 3/14 take precedence)

|  | F16K 3/18 |
· · · | by movement of the closure members

|  | F16K 3/20 |
· · · | by movement of the seats

|  | F16K 3/22 |
· | with sealing faces shaped as surfaces of solids of revolution (Fulltext... Hierarchy... Expanded...F16K 13/02 takes precedence; with resilient valve members Fulltext... Hierarchy... Expanded...F16K 3/28)

|  | F16K 3/24 |
· · | with cylindrical valve members

|  | F16K 3/26 |
· · · | with fluid passages in the valve member

|  | F16K 3/28 |
· | with resilient valve members

|  | F16K 3/30 |
· | Details

|  | F16K 3/312 |
· · | Line blinds

|  | F16K 3/314 |
· · | Forms or constructions of slides; Attachment of the slide to the spindle

|  | F16K 3/316 |
· · | Guiding of the slide

|  | F16K 3/32 |
· · | Means for additional adjustment of the rate of flow

|  | F16K 3/34 |
· · | Arrangements for modifying the way in which the rate of flow varies during the actuation of the valve

|  | F16K 3/36 |
· · | Features relating to lubrication

|  | F16K 5/00 |
Taps or cocks comprising only cut-off apparatus having at least one of the sealing faces shaped as a more or less complete surface of a solid of revolution, the opening and closing movement being predominantly rotary (taps of the lift-valve type Fulltext... Hierarchy... Expanded...F16K 1/00)

|  | F16K 5/02 |
· | with plugs having conical surfaces; Packings therefor

|  | F16K 5/04 |
· | with plugs having cylindrical surfaces; Packings therefor

|  | F16K 5/06 |
· | with plugs having spherical surfaces; Packings therefor

|  | F16K 5/08 |
· | Details

|  | F16K 5/10 |
· · | Means for additional adjustment of the rate of flow

|  | F16K 5/12 |
· · | Arrangements for modifying the way in which the rate of flow varies during the actuation of the valve

|  | F16K 5/14 |
· · | Special arrangements for separating the sealing faces or for pressing them together

|  | F16K 5/16 |
· · · | for plugs with conical surfaces

|  | F16K 5/18 |
· · · | for plugs with cylindrical surfaces

|  | F16K 5/20 |
· · · | for plugs with spherical surfaces

|  | F16K 5/22 |
· · | Features relating to lubrication

|  | F16K 7/00 |
Diaphragm cut-off apparatus, e.g. with a member deformed, but not moved bodily, to close the passage (means for plugging pipes or hoses Fulltext... Hierarchy... Expanded...F16L 55/10)

|  | F16K 7/02 |
· | with tubular diaphragm

|  | F16K 7/04 |
· · | constrictable by external radial force

|  | F16K 7/06 |
· · · | by means of a screw-spindle, cam, or other mechanical means

|  | F16K 7/07 |
· · · | by means of fluid pressure

|  | F16K 7/08 |
· · | constrictable by twisting

|  | F16K 7/10 |
· | with inflatable member

|  | F16K 7/12 |
· | with flat, dished, or bowl-shaped diaphragm

|  | F16K 7/14 |
· · | arranged to be deformed against a flat seat

|  | F16K 7/16 |
· · · | the diaphragm being mechanically actuated, e.g. by screw-spindle or cam

|  | F16K 7/17 |
· · · | the diaphragm being actuated by fluid pressure

|  | F16K 7/18 |
· | with diaphragm secured at one side only, e.g. to be laid on the seat by rolling action

|  | F16K 7/20 |
· | with a compressible solid closure member

|  | F16K 9/00 |
Arrangements for cutting-off by means of liquid or granular medium

|  | F16K 11/00 |
Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves

|  | F16K 11/02 |
· | with all movable sealing faces moving as one unit

|  | F16K 11/04 |
· · | comprising only lift valves

|  | F16K 11/06 |
· · | comprising only sliding valves

|  | F16K 11/07 |
· · · | with cylindrical slides

|  | F16K 11/08 |
· · | comprising only taps or cocks

|  | F16K 11/10 |
· | with two or more closure members not moving as a unit

|  | F16K 11/12 |
· · | with one plug turning in another

|  | F16K 11/14 |
· · | operated by one actuating member, e.g. a handle (with one plug turning in another Fulltext... Hierarchy... Expanded...F16K 11/12)

|  | F16K 11/16 |
· · · | which only slides, or only turns, or only swings in one plane

|  | F16K 11/18 |
· · · | with separate operating movements for separate closure members

|  | F16K 11/20 |
· · | operated by separate actuating members (with one plug turning in another Fulltext... Hierarchy... Expanded...F16K 11/12)

|  | F16K 11/22 |
· · · | with an actuating member for each valve, e.g. interconnected to form multiple-way valves

|  | F16K 11/24 |
· · · | with an electromagnetically-operated valve, e.g. for washing machines

|  | F16K 13/00 |
Other constructional types of cut-off apparatus (means for plugging pipes or hoses Fulltext... Hierarchy... Expanded...F16L 55/10)

|  | F16K 13/02 |
· | with both sealing faces shaped as small segments of a cylinder and the moving member pivotally mounted

|  | F16K 13/04 |
· | with a breakable closure member

|  | F16K 13/06 |
· · | constructed to be ruptured by an explosion

|  | F16K 15/00 - F16K 23/00 |
Functional types

|  | F16K 15/00 |
Check valves (adapted especially for inflatable balloons Fulltext... Hierarchy... Expanded...A63B 41/00)

|  | F16K 15/02 |
· | with guided rigid valve members

|  | F16K 15/03 |
· · | with a hinged closure member

|  | F16K 15/04 |
· · | shaped as balls

|  | F16K 15/06 |
· · | with guided stems

|  | F16K 15/08 |
· · | shaped as rings

|  | F16K 15/10 |
· · · | integral with, or rigidly fixed to, a common valve plate

|  | F16K 15/12 |
· · | Springs for ring valves

|  | F16K 15/14 |
· | with flexible valve members

|  | F16K 15/16 |
· · | with tongue-shaped laminae

|  | F16K 15/18 |
· | with actuating mechanism; Combined check valves and actuated valves

|  | F16K 15/20 |
· | Specially designed for inflatable bodies, e.g. tyres (combinations of valves with inflatable bodies Fulltext... Hierarchy... Expanded...B60C)

|  | F16K 17/00 |
Safety valves; Equalising valves

|  | F16K 17/02 |
· | opening on surplus pressure on one side; closing on insufficient pressure on one side (check valves Fulltext... Hierarchy... Expanded...F16K 15/00)

|  | F16K 17/04 |
· · | spring-loaded

|  | F16K 17/06 |
· · · | with special arrangements for adjusting the opening pressure

|  | F16K 17/08 |
· · · | with special arrangements for providing a large discharge passage

|  | F16K 17/10 |
· · · | with auxiliary valve for fluid operation of the main valve

|  | F16K 17/12 |
· · | weight-loaded

|  | F16K 17/14 |
· · | with fracturing member

|  | F16K 17/16 |
· · · | with fracturing diaphragm

|  | F16K 17/164 |
· · | and remaining closed after return of the normal pressure

|  | F16K 17/168 |
· · | combined with manually-controlled valves, e.g. a valve combined with a safety valve

|  | F16K 17/18 |
· | opening on surplus pressure on either side

|  | F16K 17/19 |
· · | Equalising valves predominantly for tanks

|  | F16K 17/192 |
· · · | with closure member in the form of a movable liquid column

|  | F16K 17/194 |
· · · | weight-loaded

|  | F16K 17/196 |
· · · | spring-loaded

|  | F16K 17/20 |
· | Excess-flow valves (actuated in consequence of shock or similar extraneous influence Fulltext... Hierarchy... Expanded...F16K 17/36)

|  | F16K 17/22 |
· · | actuated by the difference of pressure between two places in the flow line

|  | F16K 17/24 |
· · · | acting directly on the cutting-off member

|  | F16K 17/26 |
· · · · | operating in either direction

|  | F16K 17/28 |
· · · · | operating in one direction only

|  | F16K 17/30 |
· · · · · | spring-loaded

|  | F16K 17/32 |
· · · | acting on a servo-mechanism or on a catch-releasing mechanism

|  | F16K 17/34 |
· · | in which the flow-energy of the flowing medium actuates the closing mechanism

|  | F16K 17/36 |
· | actuated in consequence of extraneous circumstances, e.g. shock, change of position

|  | F16K 17/38 |
· · | of excessive temperature

|  | F16K 17/40 |
· | with a fracturing member, e.g. fracturing diaphragm, glass, fusible joint (valves opening on surplus pressure Fulltext... Hierarchy... Expanded...F16K 17/14)

|  | F16K 17/42 |
· | Valves preventing penetration of air in the outlet of containers for liquids

|  | F16K 19/00 |
Valve arrangements specially adapted for mixing fluids coming from different conduits; Valve fittings with mixing devices (multiple-way valves Fulltext... Hierarchy... Expanded...F16K 11/00)

|  | F16K 21/00 |
Fluid-delivery valves (for liquid handling Fulltext... Hierarchy... Expanded...B67D; for flushing devices for water-closets or the like Fulltext... Hierarchy... Expanded...E03D)

|  | F16K 21/02 |
· | providing a continuous small flow

|  | F16K 21/04 |
· | Self-closing valves, i.e. closing automatically after operation

|  | F16K 21/06 |
· · | in which the closing movement, either retarded or not, starts immediately after opening

|  | F16K 21/08 |
· · · | with ball-shaped closing members

|  | F16K 21/10 |
· · · | with hydraulic brake cylinder acting on the closure member

|  | F16K 21/12 |
· · · | with hydraulically-operated opening means; with arrangements for pressure relief before opening

|  | F16K 21/14 |
· · | with special means for preventing the self-closing

|  | F16K 21/16 |
· · | closing after a predetermined quantity of fluid has been delivered (Fulltext... Hierarchy... Expanded...F16K 21/10 takes precedence)

|  | F16K 21/18 |
· · | closed when a rising liquid reaches a predetermined level (float-actuated valves Fulltext... Hierarchy... Expanded...F16K 31/18)

|  | F16K 21/20 |
· · · | by means making use of air-suction through an opening closed by the rising liquid

|  | F16K 23/00 |
Valves for preventing drip from nozzles

|  | F16K 25/00 - F16K 51/00 |
Details (venting or aerating means Fulltext... Hierarchy... Expanded...F16K 45/00)

|  | F16K 25/00 - F16K 51/00 |
Note(s) Details not provided for in the following groups are classified in the preceding groups.

|  | F16K 25/00 |
Details relating to contact between valve members and seats (sealing constructions, see the appropriate groups according to the type of valve; movement of valve members other than for opening and closing Fulltext... Hierarchy... Expanded...F16K 29/00)

|  | F16K 25/02 |
· | Arrangements using fluid issuing from valve members or seats

|  | F16K 25/04 |
· | Arrangements for preventing erosion, not otherwise provided for

|  | F16K 27/00 |
Construction of housings (methods for welding housings Fulltext... Hierarchy... Expanded...B23K); Applications of materials therefor

|  | F16K 27/02 |
· | of lift valves (for reducing the flow resistance of screw-spindle lift-valves Fulltext... Hierarchy... Expanded...F16K 1/06)

|  | F16K 27/03 |
· · | specially adapted for tank-cars

|  | F16K 27/04 |
· | of sliding valves

|  | F16K 27/06 |
· | of taps or cocks

|  | F16K 27/08 |
· | Guiding yokes for spindles; Means for closing housings; Dust caps, e.g. for tyre valves

|  | F16K 27/10 |
· | Welded housings

|  | F16K 27/12 |
· | Covers for housings

|  | F16K 29/00 |
Arrangements for movement of valve members other than for opening and closing the valve, e.g. for grinding-in, for preventing sticking

|  | F16K 29/02 |
· | providing for continuous motion

|  | F16K 31/00 |
Operating means; Releasing devices

|  | F16K 31/02 |
· | electric; magnetic

|  | F16K 31/04 |
· · | using a motor

|  | F16K 31/05 |
· · · | specially adapted for operating hand-operated valves or for combined motor and hand operation

|  | F16K 31/06 |
· · | using a magnet

|  | F16K 31/08 |
· · · | using a permanent magnet

|  | F16K 31/10 |
· · · | with additional mechanism between armature and closure member

|  | F16K 31/12 |
· | actuated by fluid (fluid-actuated check valves Fulltext... Hierarchy... Expanded...F16K 15/00; fluid-actuated safety valves Fulltext... Hierarchy... Expanded...F16K 17/00)

|  | F16K 31/14 |
· · | for mounting on, or in combination with, hand-actuated valves

|  | F16K 31/143 |
· · · | the fluid acting on a piston

|  | F16K 31/145 |
· · · | the fluid acting on a diaphragm

|  | F16K 31/16 |
· · | with a mechanism, other than pulling- or pushing-rod, between fluid motor and closure member (with float Fulltext... Hierarchy... Expanded...F16K 31/18)

|  | F16K 31/163 |
· · · | the fluid acting on a piston

|  | F16K 31/165 |
· · · | the fluid acting on a diaphragm

|  | F16K 31/18 |
· · | actuated by a float (floats Fulltext... Hierarchy... Expanded...F16K 33/00)

|  | F16K 31/20 |
· · · | actuating a lift valve

|  | F16K 31/22 |
· · · · | with the float rigidly connected to the valve

|  | F16K 31/24 |
· · · · | with a transmission with parts linked together from a single float to a single valve

|  | F16K 31/26 |
· · · · · | with the valve guided for rectilinear movement and the float attached to a pivoted arm

|  | F16K 31/28 |
· · · · | with two or more floats actuating one valve

|  | F16K 31/30 |
· · · | actuating a gate valve or sliding valve

|  | F16K 31/32 |
· · · | actuating a tap or cock

|  | F16K 31/34 |
· · · | acting on pilot valve controlling the cut-off apparatus

|  | F16K 31/36 |
· · | in which fluid from the conduit is constantly supplied to the fluid motor

|  | F16K 31/363 |
· · · | the fluid acting on a piston (Fulltext... Hierarchy... Expanded...F16K 31/38 takes precedence)

|  | F16K 31/365 |
· · · | the fluid acting on a diaphragm

|  | F16K 31/38 |
· · · | in which the fluid works directly on both sides of the fluid motor, one side being connected by means of a restricted passage and the motor being actuated by operating a discharge from that side (Fulltext... Hierarchy... Expanded...F16K 31/40 takes precedence)

|  | F16K 31/383 |
· · · · | the fluid acting on a piston

|  | F16K 31/385 |
· · · · | the fluid acting on a diaphragm

|  | F16K 31/40 |
· · · | with electrically-actuated member in the discharge of the motor

|  | F16K 31/42 |
· · | by means of electrically-actuated members in the supply or discharge conduits of the fluid motor (Fulltext... Hierarchy... Expanded...F16K 31/40 takes precedence)

|  | F16K 31/44 |
· | Mechanical actuating means

|  | F16K 31/46 |
· · | for remote operation

|  | F16K 31/48 |
· · | actuated by mechanical timing-device, e.g. with dash-pot (self-closing valves Fulltext... Hierarchy... Expanded...F16K 21/16)

|  | F16K 31/50 |
· · | with screw-spindle

|  | F16K 31/52 |
· · | with crank, eccentric, or cam

|  | F16K 31/524 |
· · · | with a cam

|  | F16K 31/528 |
· · · | with pin and slot

|  | F16K 31/53 |
· · | with toothed gearing

|  | F16K 31/54 |
· · · | with pinion and rack

|  | F16K 31/56 |
· · | without stable intermediate position, e.g. with snap action

|  | F16K 31/58 |
· · | comprising a movable discharge-nozzle

|  | F16K 31/60 |
· · | Handles

|  | F16K 31/62 |
· · | Pedals or like operating members, e.g. actuated by knee or hip

|  | F16K 33/00 |
Floats for actuation of valves or other apparatus

|  | F16K 35/00 |
Means to prevent accidental or unauthorized actuation

|  | F16K 35/02 |
· | to be locked or disconnected by means of a push or pull

|  | F16K 35/04 |
· | yieldingly resisting the actuation

|  | F16K 35/06 |
· | using a removable actuating or locking member, e.g. a key (Fulltext... Hierarchy... Expanded...F16K 35/10, Fulltext... Hierarchy... Expanded...F16K 35/12 take precedence)

|  | F16K 35/08 |
· | requiring setting according to a code, e.g. permutation locks

|  | F16K 35/10 |
· | with locking caps or locking bars

|  | F16K 35/12 |
· | with sealing wire

|  | F16K 35/14 |
· | interlocking two or more valves

|  | F16K 35/16 |
· | with locking member actuated by magnet

|  | F16K 37/00 |
Special means in or on valves or other cut-off apparatus for indicating or recording operation thereof, or for enabling an alarm to be given

|  | F16K 39/00 |
Devices for relieving the pressure on the sealing faces

|  | F16K 39/02 |
· | for lift valves

|  | F16K 39/04 |
· | for sliding valves

|  | F16K 39/06 |
· | for taps or cocks

|  | F16K 41/00 |
Spindle sealings

|  | F16K 41/02 |
· | with stuffing-box

|  | F16K 41/04 |
· · | with at least one ring of rubber or like material between spindle and housing

|  | F16K 41/06 |
· · | with at least one ring attached to both spindle and housing

|  | F16K 41/08 |
· · | with at least one ring provided with axially-protruding peripheral closing-lip

|  | F16K 41/10 |
· | with diaphragm, e.g. shaped as bellows or tube

|  | F16K 41/12 |
· · | with approximately flat diaphragm

|  | F16K 41/14 |
· | with conical flange on the spindle which co-operates with a conical surface in the housing

|  | F16K 41/16 |
· | with a flange on the spindle which rests on a sealing ring

|  | F16K 41/18 |
· · | sealing only when the closure member is in the opened position

|  | F16K 43/00 |
Auxiliary closure means in valves, which in case of repair, e.g. rewashering, of the valve, can take over the function of the normal closure means; Devices for temporary replacement of parts of valves for the same purpose

|  | F16K 45/00 |
Means, e.g. valves, for venting or aerating (equalising valves Fulltext... Hierarchy... Expanded...F16K 17/00; aerating-means for use in pipes Fulltext... Hierarchy... Expanded...F16L 55/06; apparatus for draining-off, or releasing, liquid from containers or pipe-lines Fulltext... Hierarchy... Expanded...F16T)

|  | F16K 45/02 |
· | for venting of superfluous air

|  | F16K 45/04 |
· | for aeration

|  | F16K 47/00 |
Means in valves for absorbing fluid energy (for pipes Fulltext... Hierarchy... Expanded...F16L 55/00)

|  | F16K 47/02 |
· | for preventing water-hammer or noise

|  | F16K 47/04 |
· | for decreasing pressure, the throttle being incorporated in the closure member

|  | F16K 47/06 |
· · | with a throttle in the form of a helical channel

|  | F16K 47/08 |
· | for decreasing pressure and having a throttling member separate from the closure member

|  | F16K 47/10 |
· · | in which the medium in one direction must flow through the throttling channel, and in the other direction may flow through a much wider channel parallel to the throttling channel

|  | F16K 47/12 |
· · | the throttling channel being of helical form

|  | F16K 47/14 |
· · | the throttling member being a perforated membrane

|  | F16K 47/16 |
· · | the throttling member being a cone

|  | F16K 49/00 |
Means in or on valves for heating or cooling (for pipes Fulltext... Hierarchy... Expanded...F16L 53/00; thermal insulation in connection with pipes or pipe systems Fulltext... Hierarchy... Expanded...F16L 59/16)

|  | F16K 51/00 |
Other details not peculiar to particular types of valves or cut-off apparatus