Maintenance and Service 8-15
Figure 8-10
Installing a Saturator Wick
Bypass/Makeup Air Flow Adjustment
Refer to the flow schematic in Figure 5-1.
High inlet flow is adjustable using the bypass/makeup air variable
orifice. The bypass/makeup air is nominally 1.2 L/min. Together
with nominally 0.3 L/min aerosol flow, 1.5 L/min inlet sample flow
is produced. Aerosol flow is not adjustable because it is controlled
by the critical orifice.
To make adjustments to the bypass/makeup air flow, you must
have a suitable flowmeter as a reference. Choose an external
flowmeter that has a low pressure drop and measure the actual
volumetric flow e.g., a bubble meter or a TSI flowmeter. If you use a
mass flowmeter (one referenced to standard conditions), convert the
standard flow to actual (volumetric) flow with the following
equation:
⎟
⎠
⎞
⎜
⎝
⎛
××=
P
T
sscmscm
35.101
293
)/( flow std)/(flow Actual
33
where T = °K
P = kPa
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