Transcript Fittings module general introduction
Fittings and Tube
For the interconnection of pneumatic components and systems
Contents
Introduction
Presentations
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Introduction
Fittings connect the components of a pneumatic system with flexible tubing, hose and rigid pipe A variety of fittings ranges are produced to fulfil the needs of general and specific industries The variables include:
methods of connection thread sizes tube sizes
angles of connection number of connections materials of construction applications industry standards
Thread sizes
For the majority of pneumatic applications fittings will be required in the ranges: R 1 / 8 , R 1 / 4 , R 3 / 8 , R 1 / 2 , R 3 / 4 M 5, G 1 / 8 , G 1 / 4 , G 3 / 8 , G 1 / 2 , G 3 / 4 , G 1 NPTF 1 / 8 , 1 / 4 , 3 / 8 , 1 / 2
Tube sizes
Tube sizes are identified by their o/d (outside diameter) The metric range covers 4, 5, 6, 8, 10, 12, 14, 16, 22, 28 mm o/d The inch range covers 1 / 8 , 5 / 32 , 3 / 16 , 1 / 4 , 5 / 16 , 3 / 8 , 1 / 2 , 5 / 8 , 3 / 4 o/d
Tube and hose materials
Plastics
Polyamide ( Nylon )
Nylon, food grade Polyurethane Terylene braided PVC Metal braided rubber Weld tube Copper
Annealed Half hard standard duty Half hard heavy duty Steel
Double wall brazed
Types of Pneumatic Fittings
Push-In Fittings, very quick joint with the tube Push-On Fittings, neat, quick joint using a finger tight nut Compression Fittings, firm joint, for plastic or metal tube:
internal nut version external nut version
Industry specific fittings
Plasfit, hygienic, food grade plastic push in fittings designed for use in drinks dispense and brewing industries FleetFit, brass push-in fittings with tube support, for vehicle air braking systems and auxiliary systems WeldFit, nickel plated brass push-in fittings with tube support, for use with WeldTube to protect against damage from weld spatter.
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General purpose fittings
BSP and Hose taper and parallel fittings Nickel plated brass construction
Adaptors Connectors Reducers Expanders Bulkheads Tees Elbows Unions Hose connectors Banjos
Function fittings
Pneumatic sensor
Senses the falling exhaust pressure in an actuator and sends a signal when it has stopped Blocking
Activated by removing a pneumatic pilot signal to block flow one way Pressure reducing
Placed in the line to one end of a cylinder to reduce pressure
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Thread standards (Europe) Fittings
Taper male threads comply with ISO 7 (BS 21) and are designated by R 1 / 8 , R 1 / 4 , R 3 / 8 , R 1 / 2 etc.
Parallel male and female threads comply with ISO 228 (BS 2779) and are designated G 1 / 8 , G 1 / 4 , G 3 / 8 , G 1 / 2 etc.
Parallel metric threads are to ISO 261 (BS3643) designated M5x1, M10x1, M12x1.5, etc.
Ports
The ports in components such as cylinders and valves are parallel and comply to ISO 228 (BS2779) these are designated G 1 / 8 , G 1 / 4 , G 3 / 8 , etc.
Parallel metric threads are to ISO 261 (BS3643) designated M5x1, M10x1, M12x1.5, etc.
Thread standards (USA) Fittings
Dryseal threads are taper male threads NPTF “National (American) Standard Pipe Taper Fuel and Oil” Sizes show TPI (threads per inch). The most popular range for 1 industrial pneumatics are / 8 -27, 1 / 4 -18, 3 / 8 -18, 14, 3 / 4 -14 1 / 2 -
Ports
The ports in components such as cylinders and valves are NPTF. This provides a male taper to female taper joint.
NPSF and NPSI parallel female threads also allow connection with male taper NPTF fittings
Sealing the thread
Parallel threaded fittings seal on a washer between the fitting and the face of the component’s port. The surround to the port is usually spot face machined Taper threaded fittings rely on a lightly wedged fit and use sealant between the threads of the fitting and port
Taper to parallel
Taper fittings are made smaller in diameter as there is no bearing surface required for a washer Taper fittings do not require the port to be spot faced so are suitable for ports in unmachined components and ports at an angle to their surface By manufacturing to selected tolerances taper fittings are successfully used with parallel ports This combination is very popular in many sectors of the pneumatics industry Fittings must not be over tightened, particularly for ports in thin wall cast material as there is a risk of cracking the casting
Working pressure ranges
The safe working pressure for the majority of pneumatic systems is 10 bar maximum with some components up to 16 bar maximum Most fittings will be safe at pressures in excess of these but obtain advice Plastic tubing is limited by wall thicknes and operating temperature Metal tubing has a higher rating Pressure Max from Vacuum
Pneufit 18 bar *
FleetFit WeldFit 10 bar 18 bar *
Plasfit 10 bar Limited by plastic tube
Push-on 9 to 11 bar
Compression 15 to 28 bar * If tubing allows and not including regulating banjos which are 10 bar
Working temperature ranges
Temperatures are generally limited by the plastic and rubber parts of a fitting and the tube material For extreme temperatures use compression fittings and metal tube. Also choose taper threads Where parallel threaded fittings are supplied with plastic washers the temperature is limited to - 40 O C to 70 O C
Push- in Range
Pneufit -20 0 C to 70 0 C
Plasfit 0 0 C to 70 0 C Fleetfit - 40 0 C to 100 0 C Weldfit - 30 0 C to 70 0 C Push- on
24 Series 0 O C to 70 O C Compression fittings with metal tube at 10 bar
- 40 to +100 O C BSP and Hose
limited by tube or hose
End
Pressure rating
Plastic tube O/D mm bar maximum Polyamide (PA) 4 28 Polyurethane (PU) 10 5 31 11 6 8 25 10 19 9 10 12 14 16 22 24 9 18 9 15 18 15 28 15 Pressure values are for a temperature range -40 O C to +20 O C For compressed air above 16 bar consult our technical service Higher temperatures O C Pressure adjustment factor 30 40 50 60 80 0.83 0.72 0.64 0.57 0.47
Pressure rating
Copper and steel tube O/D mm bar maximum Copper Annealed Copper Half Hard Steel 4 5 6 8 10 12 16 128 138 112 81 64 81 193 208 218 157 150 122 300 250 195 160 59 89 22 53 81 28 41 62 Pressure values are for a temperature range -40 O C to +50 O C For compressed air above 16 bar consult our technical service Pressure adjustment factors O C Annealed Half Hard 100 150 175 200 0.97 0.82 0.63 0.43
0.95 0.88 0.54 0.29