Measure during demand, not during a break
At rest, pressure gauges may show almost the same pressure. It is only during flow that pressure losses become apparent. The critical value is the lowest pressure at the greatest relevant simultaneous demand, including the lower limit of the compressor's control band. A brief pressure dip must be distinguished from a persistent supply shortage.
How to reduce pressure without jeopardising production
First verify equipment requirements and record pressure profiles in the compressor room and at the affected consumer. Clean or correctly size restrictions along the path. Only then adjust settings, observing the equipment's safety and design limits. Determine savings from actual performance data, not a universal percentage.
What to check in practice
- Record the consumer's minimum and maximum allowable pressure.
- Include losses under flow and filter fouling during operation in the pressure balance.
- Consider a separate solution for a single consumer requiring substantially higher pressure.
Example scenario
A consumer requires at least 6 bar(g). At design flow, the path loses 0.6 bar. Pressure at the start of that path must therefore be at least 6.6 bar(g); operating reserve and control band are determined separately. This is not a blanket recommendation to set every compressor to 6.6 bar.
What to watch out for
- Reducing pressure without checking the worst operating condition.
- Compensating for an undersized quick coupling by raising the pressure of the whole network.
- Confusing bar(g) with bar(a).
Why does pressure at the machine fall even though the compressor is large enough?
The cause may be a narrow hose, regulator, clogged filter or short demand peak. Simultaneous pressure logging at several points helps distinguish insufficient generation from a restriction in the distribution system.