ERWEKA Vacuum Pump Type VP 1000 The ERWEKA Vacuum Pump VP 1000 used for testing MDI's and DPI's employs a Rotary Vane Vacuum Pump rated at 250 litres/ min. free air (210 Litres/min. when used with the control valve). The unit is supplied complete with an Electronic Digital Flow Meter as standard. The air-flow is controlled by means of the screw valve on the front of the pump. The screw valve itself creates a restriction to the air flow such that the minimum flow rated achievable is approximately 210 litres/min.

ERWEKA High Power Vacuum Pump, HPV

The standard pump VP 1000 rated at 250 litres/min free air (i.e., with nothing attached to it). However, this flow rate can fall dramati-cally when the resistance of both test device and inhaler are taken into account. For tests where the flow-rate of the standard pump is not enough to create a Sonic-Flow a second “High-Power” version of the ERWEKA Vacuum Pump, Type HPV, is available. This Rotary Vane Vacuum Pump rated at 460 litres/min free air.

Basically, there are two factors that govern the ability of a particular pump to achieve sonic flow 

1. The maximum capacity (air-flow) of the vacuum pump
2. The resistance to that air flow provided by the test device (Andersen, MSLI etc.) and the inhaler itself