Selecting Appropriate Outlet Nozzles - Palas VKL 10 Operation Manual

O M VKL 10 /100
PERATION ANUAL

6.2. Selecting Appropriate Outlet Nozzles

A partial flow rate V is taken from the total flow rate of the diluted aerosol by means of the
ab
outlet nozzle. The take-out must be done isokinetically. Since the measuring instrument
used determines the partial flow rate, the isokinetic adaptation must ensue from
appropriate measures inside the dilution stage. There are two possibilities for the
adaptation. The modification of the total volume flow is one possibility (this is done by
changing the pre-pressure), or the change of the diameter of the outlet nozzle, as the second
possibility. The total volume flow can be modified within the range of 20 and 50 l/min, with
a stable dilution factor (see calibration certificate in the appendix of this manual).
Consequently, by changing the pre-pressure, we have the possibility, given a certain outlet
nozzle diameter, to adapt isokinetically such partial volume flows that differ up to the factor
of 2.5.
There are various measuring instruments on the market, with volume flows that vary from
0.3 l/min. to 28 l/min. In order to guarantee the isokinetic adaption within this wide range,
outlet nozzles with different diameters are available. The standard jet has a diameter that
guarantees isokinetic conditions when both, outlet and inlet flow rate, are the same, i.e.: the
standard dilution stage is suitable for measuring instruments with a flow rate from 1 to 5
l/min.
For measuring instruments with 28 l/min a bigger nozzle instead of the standard nozzle is
used, for measuring instruments with 0.3 l/min a smaller nozzle is installed. The respective
flow rate of the equipment must be indicated when ordering.
For VKL 100, the same outlet nozzles can be used as for VKL 10. In order to achieve exact
isokinetic conditions, the clean air volume flow rate has to be lower by 10 % than for the VKL
10. When changing the nozzle, the old nozzle is pulled out of the outlet opening, and the
new nozzle is pushed in until it arrests.
V V005-06-2020 18
ERSION