SKC Limited Pocket Pump MTX - Manual (Page 24)

Page 22 210-PMTXM Issue F www.skcltd.com
Through Flow Sampling with the Twin Port Pocket Pump
2) Constant pressure mode sampling
With the Pocket Pump set to constant pressure mode it is possible to obtain a stable pump flow rate with
variable outlet back pressures (up to 30 inches of water). An adjustable flow restrictor at the pump inlet is
required to set the desired flow rate. Note that once the required flow rate has been set, the sample train inlet
flow restriction must remain constant during sampling.
Constant pressure mode compensation performance: With a constant inlet restriction of 5 inches of
water, the pump flow rate will be within ±5% with outlet back pressure of 30 inches of water up 100 ml/min
flow rate, and with outlet back pressure of 20 inches of water up to 200 ml/min flow rate.
To set the pump up for constant pressure mode through flow sampling applications:
Ensure that the pump is set to Constant Pressure mode and that the battery is fully charged. Connect the
sample train including the adjustable flow restrictor to the pump air inlet port.
Press [ ] to start the pump running.
Press . The LCD screen will show the back pressure setting screen with ‘ SET’
and ‘ ’ flashing.
Use the and buttons to set a suitable back pressure in inches of water or mm of
mercury, e.g. 5.0 inches of water (or higher if the inlet sample train is more restrictive),
on the LCD screen.