40
rate value (A-axis) plot a line up to the value of the outer diameter of the pipe (B axis). This straight line intersects the R axis at a point x. From x draw a straight line up to the value of pressure (C axis). The intersection between the extension of this line and the A-axis indica- tes the value of the loss of load of the pipe.
NOTE: the scale on the graph is expressed in NRA (Normal Reference Atmosphere) defined as: actual flow rate to the actual pressure (P) x absolute pressure (P+1) [bar]
The graph is referenced to a fluid temperature of 15°C. For different temperature values you need to enter a correction factor of temperature. For example, you have to evaluate a flow rate at 0 ° C: flow rate at 0°C = flow rate at 15°C x 0°C+273 288
12.2. Load Losses of the fittings
The fittings, being smooth on the inside and having the same internal diameter as the pipes, create nevertheless, an obstacle to the air flow in a particular way when determining a change in direction, as in the case of curves, T and reductions. The following table shows the data for the load losses caused by fittings. Each fitting or direction change corresponds to X metres of pipe as specified in the table.
Diam. Outer
T in
Sleeves
Elbows 90°
T in line
Reductions
deviation
pipe 20
0,15
0,40
0,20
0,60
0,20
0,20
0,50
0,30
0,80
0,25
25
0,25
0,60
0,40
1,10
0,35
32
0,30
0,80
0,50
1,40
0,45
40
0,40
0,95
0,70
1,70
0,60
50
0,50
1,25
0,95
2,30
0,75
63
12.3. Network dimensioning
Having noted the compressed air consumption expressed in l / min. and established the acceptable load loss, reference is made to the graph to determine the size of the pipes. Having examined the system and considered changes of direction, Ts and reductions, complete and correct the previously evaluated infor- mation with the data from the table above.
13. RESIDUAL RISKS
The pipes and fittings can generate the following residual risks in case of non-compliance with safety information and requirements provided in these operating instructions: - Risk of fluid ejections under pressure in case of disconnection of connections caused by inadequate tightening. - Risk of ejections of fluids under pressure in the event of damage to the pipe caused by shocks. - Risk of ejections of fluid under pressure caused by operating pressures higher than the maximum allowable pressure of 12.5 bar.
14. MAINTENANCE
IMPORTANT Any type of intervention should be performed on the system when it has been depressurised.
The table below shows a list of checks and controls recommended by SICOMAT: - Annually review the status of the systems - Check the tightening of the nuts - In case of shock, check the status of the pipeline; in case of damage replace the damaged parts.
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