Fittings and Tube

For the interconnection of pneumatic components and systems

Contents

Thread sizes Tube sizes and materials Fitting types Industry specific fittings General purpose fittings Function fittings Standards Sealing the thread Taper and parallel Pressures / temperatures

Pneufit Push-on fittings External nut compression Internal nut compression BSP and Hose fittings FleetFit (vehicle fittings)

WeldFit (welding industry ) Plasfit (brewing industry)

Tube and Hose

Presentations

Click the section or presentation to go to it

Introduction

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.

8 m m8 m m

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 industrial pneumatics are 1/8 -27, 1/4 -18, 3/8 -18, 1/2-14, 3/4 -14

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 10 bar WeldFit 18 bar * Plasfit 10

bar

Limited by plastic tube Push-on 9 to 11 bar Compression 15 to 28 bar

* If tubing allows andnot including regulating banjos which are 10 barTubing details

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- 40OC to 70OC

Push- in Range Pneufit -200C to

700C Plasfit 00C to

700C Fleetfit - 400C to 1000C Weldfit - 300C to 700C

Push- on 24 Series 0OC to 70OC

Compression fittings with metal tube at 10 bar

- 40 to +100OC BSP and Hose

limited by tube or hose

End

Pressure rating

O/D mm 4 5 6 8 10 12 14 16 22 28

Polyamide (PA) 28 31 25 19 24 18 15 18 15 15

Polyurethane (PU) 10 11 10 9 9 9

Pressure values are for a temperature range -40 OC to +20 OC

Higher temperatures OC

Pressure adjustment factor

30 40 50 60 80

0.83 0.72 0.64 0.57 0.47

bar maximum

Plastic tube

For compressed air above 16 bar consult our technical service

Pressure rating

O/D mm 4 5 6 8 10 12 16 22 28

128 138 112 81 64 81 59 53 41

Pressure values are for a temperature range -40 OC to +50 OC

Copper Annealed

Copper Half Hard 193 208 218 157 150 122 89 81 62

bar maximum

Copper and steel tube

Steel 300 250 195 160

OCAnnealed

100

Half Hard

150 175 2000.97 0.82 0.63 0.43

0.95 0.88 0.54 0.29

Pressure adjustment factors

For compressed air above 16 bar consult our technical service

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