Flow rate control

Flow rate control

The flow rate control is obtained through a pneumatic mechanism incorporated in the compressor, which by-passes part of the gas in the compression phase, at the intake, i.e. in the low pressure chamber.

When activated, this system makes it possible to reduce the compressor flow rate gradually and continuously to appr. 17% of the total capacity.

The mechanism comprises the piston (A) which can run in the cylinder (C) countered by the spring (B).

When the piston is positioned as shown in figure A, it cuts off holes (D) which connect compartment (E) - in which the gas begins to be compressed - with the low pressure chamber (F). Conversely, when the piston (A) is in the position shown in Figure B, the holes (D) connect the two chambers.

The piston is operated by a small amount of the pressurised gas withdrawn from duct (J) which communicates with the calibrated hole (G).

The pressure regulator (H) is adjusted by the difference in pressure between intake - chamber (F) - and delivery: when the intake pressure is high valve (I) is closed, and the pressure of the gas acts on piston (A) taking it to the position of figure A. Holes (D) are cut off and by-passing does not take place. This starts off compression of the gas in chamber (E) as described.

When the intake pressure falls, the regulator (H) opens the valve (I) allowing the pressurised gas in duct (J) and in cylinder (C), to discharge into the low pressure chamber (F). Becase of, piston (A) is pushed by the spring (B) allowing the by-pass holes (D) to open.

This way, part of the gas in chamber (E) - start of compression - can flow into the low pressure chamber (F), until blade (K) has covered the holes (D); this reduces the amount of gas in chamber (E) resulting in the reduction of the compressor flow rate.