Valve Basics

1、4 5 1 3 2 8482 12/14 1214 Inside Sales Training Pneumatic Directional Control Valves Valves in pneumatics Directional control valves Check Valves Pressure regulation valves Flow control valves 4 5 1 3 2 8482 12/14 1214 What is a Directional Control Valve? lA mechanical device used to direct the flow

2、 of a fluid- pneumatic directional control valves are used to direct air flow. lValves are described by: lFlow Directions lNormal or Start Condition lNumber of Ports lOperator Type lNumber of Positions Directional control valves The logic control device for pneumatics Selection of flow paths Switchi

3、ng positions for control purpose Equivalent to the switch or relay in electrical circuit Ports and positions 3/2, 5/2 etc. The basic valve body The number of main ports for inlet (1), outlets/cylinder (2, 4) and exhausts (3,5) describes the valve type. The nos of positions to follow after the / comp

4、lete the description. 5/2 valve Nos of ports (ways) / Positions 2/2 = e.g. shut off valves 3/2 = e.g. poppet valves for start, stop and signals 5/2 = e.g. solenoid valves for cylinders 5/3 = e.g. valves for stopping cylinder in position wanted 5 1 3 4 2 5 1 3 4 2 2 or 3, more very unusual 2, 3, 4 or

5、 5, more very unusual Activation To move the control element one way an activation device is needed There are four main categories of activation power: Electrical (also called solenoid or solenoid pilot) Air (also called pilot operated) Manual which is by manpower to a lever etc. Mechanical to a rol

6、ler, plunger, antenna etc. or a spring For return to initial/rest position another activation is needed The valve symbol Quick identifier For use in circuitry According to ISO 1219-1 from 1991 and Norgrens standard The tool box The valve body The control element 3 ports 5 ports The activations e.g.

7、solenoid spring Creating the valve symbol For a direct activated 3/2 solenoid valve with spring return and manual override The body The control element in rest or initial position The spring The body + control element activated The solenoid The manual override The ports and identification nos 1, 2,

8、3, 10, 12 The complete symbol 1 2 3 10 12 How to read the symbols? Ports (in the main body) 2 ports 3 ports 5 ports 5 ports Positions (nos of activations) 2 positions 1= First (rest or initial) position 2= Second position 3 positions 0 = Rest position (center/mid position) 1 = First position 2 = Sec

9、ond position How to read the symbols? 2 0 1 2 1 Ports and positions: P/P 2 ports & 2 positions = 2/2 3 ports & 2 positions = 3/2 5 ports & 2 positions = 5/2 5 ports & 3 positions = 5/3 How to read the symbols? Flow in one direction (port to port in arrows direction) Flow in both directions Port clos

10、ed Restriction Adjustable (flow control) External working line (connection) Internal connection Pneumatic source of energy (pressure) Exhaust with port Flow paths Electrical (solenoid/coil) Air (pilot) Manual (hand, foot, override etc.) Mechanical (roller, plunger, spring etc.) Activations and Opera

11、tors . Numbering identification The normal rules for ports Port no Connection 1 Inlet for pneumatic pressure (main air supply) 2 and 4Cylinder/Outlet ports 3 and 5 Exhaust from cylinders 12, 14 or X Pilot air to air activated valves or for external pilot supply 12/14 One port for external pilot supp

12、ly combines 12 & 14 82 & 84 Solenoid exhaust Position identification 10 = connection 1 = 0, saying flow from port 1 to nothing 12 = connect port no 1 to 2, saying flow to cylinder 14 = connect port no 1 to 4, saying flow to cylinder The complete symbol A 5/3 All Port Blocked solenoid pilot activated

13、 valve with external pilot to solenoids and captured solenoid exhaust in daily work called: A 5/3 APB sol/sol external pilot and pilot exhaust 4 5 1 3 2 8482 12/14 1214 Position 14Position 12 To cylinder Exhaust from solenoidExternal pilotExhaust from cylinder Air supply Coil Pilot head/armature Int

14、ernal transfer Spring to 0-position Exhaust from solenoid Manual override Normally closed - normally open NC - normally closed In pneumatic terms: No flow through the valve In electrical terms: Electricity through the switch NO - normally open In pneumatics terms: Flow through the valve In electrica

15、l terms: No electricity through the switch Take care with sensors and switches! Symbol in circuitry External connections - lines to cylinder and others Always connect to the box in the rest or initial position When activation change - move connections to the corresponding box Spring (10,12) in comma

16、nd Solenoid (12,14) in command 2 10 31 12 42 5 1 3 12 84 14 4 5 1 3 2 8482 12/14 1214 2 10 31 12 1 4 2 53 12 84 14 Valve function 3/2 versions 3 ports, 2 positions Normally closed, NC or normally open, NO For use with single acting cylinders and as pneumatic logic element for start, stop and as a re

17、lay. 2 10 31 12 At rest Spring in command. Exhaust 2 = 3 Activated Air signal in command. Spool moves right. Pressure 1 = 2 Valve function 5/2 versions 5 ports, 2 positions Switches the direction of two flow paths. Primarily for double acting cylinders. 1 4 2 53 12 84 14 At rest Spring in command. P

18、ressure 1 = 2 Exhaust 4 = 5 Activated Air signal in command. Spool moves right. Pressure 1 = 4 Exhaust 2 = 3 Valve function 5/3 versions 5 ports, 3 positions Switches the direction of two flow paths. Includes a mid position for blocking all ports, exhausting all ports or applying pressure to both cy

19、linder ports simultaneously. Primarily for double acting cylinders under special conditions like blocked, exhausted or pressurised in certain positions. At rest Springs in command. All ports blocked (shown) or 2 & 4 exhausted or pressure applied to ports 2 & 4. 4 5 1 3 24 5 1 3 2 Valve function 5/3

20、versions cont. 5 ports, 3 positions See previous page for details. Activated 12 Air signal on 12 in command. Spool moves left. Pressure 1 = 2 Exhaust 4 = 5 Activated 14 Air signal on 14 in command. Spool move right. Pressure 1 = 4 Exhaust 2 = 3 Valve designs Control elements Slide valves Poppet valv

21、es Solenoid valves Spool (piston) valves Dynamic seal Static seal Glandless spool Bonded spool Mixed poppet and spool valves n x 10,5 +56 n = number of stations Left end Right end 99 58,580 Poppet valves A simple and efficient construction using a flat or angular sealing principle often in a roughed

22、 design Short valve movement Large seating diameter Very High flow Minimal abrasion Minimal stiction Tolerates poor air quality Very low leakage rate Normally for 2/2 and 3/2 NO/NC for manual or mechanical activation. Double poppet for 4/2 Solenoid valves Direct activated Using the magnetic force di

23、rectly to open and close an orifice. High to medium wattage required Solenoid Pilot activated Using air to provide the force to shift the spool/poppet. Medium to low wattage required Spool valves Cylindrical sealing face for wider design capabilities Dynamic seals on spool Disc Thin lip seals Bonded spool O-ring Lapped precision spool Glandless spool and sleeve Low activation force Internal pressure balanced along the spools main axis 3/2, 5/2 and 5/3 valves mainly electrical or air act