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Rapidmain Installation Guide 

Aluminium Compressed Air Pipe Work Installation Guide 

Air Controls and Compressors Ltd 

Trafalgar Court, Waterloo Ind Estate, Widnes Cheshire. UK. 

Web: www.accltd.com. Telephone 0151 423 1750. 

Ref: Rapidmain installation guide 4b


Index 

1. Rapidmain fittings: Assembly and locking torque setting ……………………….…… 3 - 5 

2. Calculating compressed air flow ……………………….………………………………..…… 6 

4. Design layout for thermal expansion …………………………………….…………………. 7 

5. Pipe work fall and further points to consider …………………………………..……….. 8 - 9 

6. Pipe work bracket support. Bracket types and their use ……………..……………. 10 

7. Take-offs lines (branch lines) and the use of flexible pipe …………………………. 11 

Brief Specification 

Working Pressure - 0.6 to 13 bar (- 8 to 191 PSI) 

Media 

Compressed Air and other Neutral Gas 

Flow Range 20 to 63 mm 0.73 to 26.8 M/min (26 to 948 cfm) * 

Temperature Range -20 to +70 C 

* Flow rate calculated over 100 metres Single run line P1@ 8bar 

We suggest that both the installer and the user of the Rapidmain pipe 

installation carefully read this manual before its use and before carrying out any 

installation or modification work. Please also refer to the local health and 

safety guidelines and accident prevention rules and regulations. 


Trafalgar Court, Waterloo Ind Estate, Widnes Cheshire. WA8 OSZ. UK. 


Page 2


Aluminium Compressed Air Pipe Work Installation 

Rapidmain fittings: Assembly and locking torque settings 

Tightening of locking collars on fittings 

Assemble by hand or use our spanner set the correct torque. Black for the body and blue 

for the nut: See table B below 

Table B 

O D 20 25 32 40 50 63 

Torque 9 -11 11-13 12 - 15 15- 17 17 - 20 18 - 22 

L = mm 45 55 60 70 85 95 

Use the depth gauge on the spanner to mark 

the outside of the pipe: See below. 

Push the fitting up to the mark on the 

pipe and then rotate the blue locknut 

to secure. 




Page 3




Chamfer Pipe 

If you choose to use a vice to clamp the Aluminium pipe when cutting or chamfering leave 

clear at least 50mm of pipe to avoid damaging the radius diameter and pipe sealing surface. 

On larger pipe if required use a neutral lubricant or soap. 


Trafalgar Court, Waterloo Ind Estate, Widnes Cheshire. WA8 OSZ .UK. 


Page 4

____________________________________________________________________________ 


WARNING: to avoid O-Ring damage, the tube end must be chamfered before inserting 

the tube into the fittings. 

R-Range of Compressed Air distribution fittings Sizes DN 20 to 63 OD 

1.1 Before use check that all the fitting connection parts are correctly assembled. Ensure you 

check the orientation of the locking clip; if this is incorrectly assembled the integrity of the 

connection cannot be guaranteed (See Table A). 

1.2 Before inserting the tube into the fitting rotate the light-blue coupling ring until a slight 

mechanical stop is felt and no further. 

1.3 The tube must be inserted into the fitting until the tube bottoms. This can be checked by 

previously marking on the tube the length “L” indicated in Table B. 

1.4 Once the tube has been correctly inserted into the fitting, rotate the coupling ring 

completely over the first mechanical stop described in Section 1.2 above until fully tight. 

For best results it is advisable to use the “C” type spanners shown in the catalogue. 

1.5 Table B shows the torque (N/m) required for each fitting size to provide the optimum 

mechanical operation and seal. 

1.6 Table C illustrates the correct alignment for installation. Misalignment of more than 5 o 

from the horizontal could compromise the integrity of the fitting seal. 

1.7 Please refer to the specifications shown in the present catalogue for pipe and fittings 

compatibility with chemical substances that could be present in the compressed air. 

1.8 Rapidmain will not be held responsible for any damage caused by improper use of their 

products and/or non-compliance of the manufacturers assembly instructions here within. 

Table A 

How to calculate an air system pipe size 

2.1 Pressure drop through fittings 

Although fittings are smooth inside and have the same tube internal diameter, they 

nonetheless cause a resistance to air flow, particularly when tubes change direction as in 

the case of elbows, tees, couplings and reduction fittings. Table E refers to pressure 

drops caused by fittings. Every fitting or change of direction has an equivalent pipe 

length of tube indicated in this table. 

2.2 Air System pipe sizing Once the compressed air consumption (l/min) and the allowable 

pressure drop have 

been calculated, refer to Table D to select the correct tube dimension. After having 

examined the plant and considered the changes of direction as well as the pressure drop 

of fittings you can then refer to Table E to complete and correct previous calculations. 




Page 5


Calculating Compressed air flow 

Table C 

Table D 

Pressure drop for 

100 m (in bars) 

Effective 

Absolute 

Pressure 

(in bars) 

Delivery SRA * 

(in l/min) 

Outside 

diameter of 

the tube 

(mm) 

Referential 

axis 

Delivery SRA * 

Actual delivery at the effective pressure (P) x absolute pressure (P+1) in bars 

Temperature Correction: 

0 degrees + 273 Air 

delivery at 0 degrees C = delivery 15 degrees C x ________________ 

* SRA: Standard Reference Atmosphere 

288 

Using the Nomogram 

The tube diameter can be determined by first finding the flow rate in l/m and the allowable 

pressure drop. 

a. We have chosen the working pressure on the “C” axis. A straight red line has then 

been drawn connecting the working pressure to the pressure drop value on the “A” axis. 

b. Drawing this straight line allows us to locate a point on the “R” referential axis. 

c. A green line has then been drawn from the referential “R” axis to the value on the 

“A” axis which indicates plant delivery in l/min. 

d. This green line intersects on the “B” axis which shows the suitable tube diameter. 


Trafalgar Court, Waterloo Ind Estate, Widnes Cheshire. WA8 OSZ .UK. 


Page 6


Design layout for thermal expansion 

DL = DT x 0,02 x L 

A = DL x 23 

B = 0.7 x A 

Variation due to 

thermal expansion 

Introduction 

The theoretical calculations and design criteria in this 

manual are only relevant where the installation 

ambient temperature is between 15 o C and 25 o C. 

Attention! Where the installation is outside of the 

recommended ambient temperatures indicated above, 

it may be necessary to take corrective action such as 

thermal insulation of the pipe or the inclusion of 

expansion/contraction loops. 

Calculating expansion loop dimensions 

On long straight runs of pipe it may be necessary to 

insert expansion loops in the line to prevent damage 

to the pipe, due to thermal movement (expansion or 

contraction) of the pipe. 

Example 

L1 = 40 mt L2 = 40 mt DT = 50 o C 

DL = DT x 0.02 x L = 50 x 0.02 x 40 = 40 

mm A = DL x 23 = 40 x 23 = 920 mm 

B = 0.7 x A = 0.7 x 920 = 640 mm 

Legend 

A-B = Quote (mm) 

L-L1-L2 = Lengths (mt) 

DL = Expansions (mm) 

DT = Thermal range ( o C) 

M = Mobile bracket 

F = Fix bracket 

Examples of Expansion Loops 

Vertical layout (Upwards) 

Horizontal 

Vertical layout (Downwards) 

“Fixed brackets” hold the pipe firmly while “sliding brackets” allow axial movement. 




Page 7


Pipe work fall and further points to consider 

Fall of pipes 

Where possible horizontal runs should be designed to have a slight fall of (1-2%) in the direction 

of air flow to encourage drainage and collection of condensate at lower levels or at drop legs 

built within the air system, from which the condensate can be drained as required. 

Direction of air flow 

Install drains at low points where ever possible. 

Example 

Pipe Fall 


Trafalgar Court, Waterloo Ind Estate, Widnes Cheshire. WA8 OSZ. 

UK. Web: www.accltd.com. Telephone 0151 423 1750. 

Page 8


Pipe work fall and further points to consider 

To allow for system maintenance, install an adequate quantity of isolation valves in the pipe work. 

Valve 

Ball Valve 

Fixing of Pipes 

To allow for thermal movement of the pipe and to avoid stress points, the pipe should be installed 

and fixed to a secure surface of building, such as a wall, brickwork, roof support (direct or with 

hanging brackets) or the building framework using suitable “fixed and sliding brackets ” as required. 

Fixed 

bracket 

Fixed bracket 

Sliding bracket 

Fixed 

bracket 




Page 9



Pipe work bracket support. Bracket types and there use 

Bracket and Pipe support centres 

It is important to install the pipe work brackets with correct spacing. Always try to 

support the pipe joint with a bracket located within 200 to 500 mm from the pipe joint. 

Please refer to the diagram below for examples of preferred installation 

Install brackets by each joint to support 

the pipe joint 

Suggested Maximum Support Centres) 

DN 20/25 32 40 50 63 

P (MT) 2.5 3 3.5 4 4.5 

Legend 

L = Length (mt) 

P = Brackets support centre (mt) 

M = Bracket 

G = Joint 

An alternative to the “standard” aluminium expansion loop, 

is to use suitable flexible hose assembly as shown below. 

DL = DT x 0,2 x L 

B = (2 x R) + DL 1 + DL 2 

Legend 

L1-L2 = Lengths (mt) 

DL1-DL2 = Expansion (mm) 


M = Bracket 

R = Radius (mm) 

A-B = Quotes (mm) 

Quote R – A (mm) 

DN 20 25 32 40 50 63 

R (mm) 70 85 100 130 160 200 

A (mm) 370 390 500 560 600 800 

Attention! 

Tables are valid only for stainless steel flexible hoses 

type 1REX/INOX/N/321/DN. 

For other types refer to the manufacturer’s 

technical documentation 




Page10


Take-off lines (branch lines) and the use of flexible pipe 

DL = DT x 0,2 x L 

A = DL x Y 

Legend 

A = Quote (mm) 


DL = Expansion (mm) 


F = Fixed bracket 

U = Use 

Y = Calculation factor 

Calculation Factor Y 

DN 20 25 32 40 50 63 

Y 20 20 25 28 33 40 

Bends using flexible hose. 

Using a flexible hose in corners is also 

acceptable. They can be used for the change of 

direction and at the same time to compensate 

for any thermal movement. 

L min = 1000 mm 

At the end of a pipe run always 

terminate the pipe and the fitting to 

an fixed anchored point eg: Wall 

Legend 


DL1-DL2 = Expansion (mm) 

M = Bracket 

R = Radius (mm) 

L = Length of flexible pipe (mm) 

Pd 20od=0.2 b(3 psi) 6m/sec 

Pd 63od=2.5%(3 psi) 12m/sec 

Avoid installing flexible hoses with to tight a radius or where the 

hose is subject to, too much stretch 




Page 11

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