Fittings and Tube
For the interconnection of pneumatic
components and systems
Contents
Introduction
Presentations
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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
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Click the section or presentation to go to it
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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
Introduction
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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:
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methods of connection
thread sizes
tube sizes
angles of connection
number of connections
materials of construction
applications
industry standards
Thread sizes
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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
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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 / , 5/ , 3/ , 1/ , 5/ , 3/ , 1/ ,
8
32
16
4
16
8
2
5/ , 3/ o/d
8
4
Tube and hose materials
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Plastics
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Copper
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Polyamide ( Nylon )
Nylon, food grade
Polyurethane
Terylene braided PVC
Metal braided rubber
Weld tube
Annealed
Half hard standard duty
Half hard heavy duty
Steel
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Double wall brazed
Types of Pneumatic Fittings
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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:
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internal nut version
external nut version
Industry specific fittings
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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.
8mm
General purpose fittings
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BSP and Hose taper and
parallel fittings
Nickel plated brass
construction
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Adaptors
Connectors
Reducers
Expanders
Bulkheads
Tees
Elbows
Unions
Hose connectors
Banjos
Function fittings
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Pneumatic sensor
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Blocking
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Senses the falling
exhaust pressure in an
actuator and sends a
signal when it has
stopped
Activated by removing a
pneumatic pilot signal to
block flow one way
Pressure reducing
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Placed in the line to one
end of a cylinder to
reduce pressure
2
1
Thread standards (Europe)
Fittings
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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
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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
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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/ -27, 1/ -18, 3/ -18, 1/ 8
4
8
2
3
14, /4 -14
Ports
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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
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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
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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
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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
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Pneufit
18 bar *
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FleetFit
10 bar
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WeldFit
18 bar *
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Plasfit
10 bar
Limited by plastic tube
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Push-on
9 to 11 bar
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Compression 15 to 28 bar
* If tubing allows and
not including regulating
banjos which are 10 bar
Tubing details
Working temperature ranges
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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
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Push- in Range
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Push- on
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24 Series 0OC to 70OC
Compression fittings with
metal tube at 10 bar
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Pneufit
-200C to 700C
Plasfit
00C to 700C
Fleetfit - 400C to 1000C
Weldfit - 300C to 700C
- 40 to +100OC
BSP and Hose
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limited by tube or hose
End
Pressure rating
Plastic tube
O/D mm
4
5
6
8
10
12
14 16 22
28
28
31
25 19
24
18
15 18 15
15
Polyurethane (PU) 10
11
10
9
9
bar maximum
Polyamide (PA)
9
Pressure values are for a temperature range -40 OC to +20 OC
For compressed air above 16 bar consult our technical service
Higher temperatures OC
30
Pressure adjustment factor
0.83 0.72 0.64 0.57 0.47
40
50
60
80
Pressure rating
Copper and steel tube
O/D mm
4
5
6
8
10
12
16
22
28
81
64
bar maximum
Copper Annealed
128 138 112
81
59
53
41
Copper Half Hard
193 208 218 157 150 122
89
81
62
Steel
300 250 195 160
Pressure values are for a temperature range -40 OC to +50 OC
For compressed air above 16 bar consult our technical service
Pressure adjustment factors
OC
Annealed
Half Hard
100 150 175 200
0.97 0.82 0.63 0.43
0.95 0.88 0.54 0.29
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