RKI Instruments 30-0951RK LEL - Manual (Page 4)

4 • 30-0951RK LEL Sample Draw Aspirator Adapter
Description
The LEL Sample Draw Aspirator Adapter uses compressed air flowing through a venturi
to draw air into a sample chamber. The sample draw adapter screws directly onto the LEL
sensor in place of the rain shield which is normally screwed onto the detector.
Figure 1: Component Location
The sample draw adapter consists of four major components (see Figure 1): the regulator,
aspirator, sensor adapter, sensor chamber, and flowmeter.
Regulator
The regulator has an inlet port on its left side with a 1/4” tube fitting. The maximum
allowable inlet pressure is 300 psi. A gauge at the top of the regulator indicates the output
pressure. The output pressure, and sensor flow, can be adjusted using the knob on the
front of the regulator. The sensor flow rises or falls as the output pressure is increased or
decreased.
Aspirator
The aspirator inlet is connected to the output port on the right side of the regulator and
the vacuum port on top is connected to the sensor chamber. It has a venturi tube inside it
which generates a vacuum at its top port when compressed air flows through it. The
Screw Onto Combus tible
Sens or
Pres sue Gauge
As pirator
Thumbscrew (3X)
Flowmeter
Pres sure Regulator
Sens or Adapter
Sens or Chamber
Adapter Gasket (in
bottom of adapter)
1/4 O.D. Tube
Compres sed Air
Inlet Fitting
Pres sure Adjus tment
Knob
As pirator/Sample
Ex haust
(1/8 NPT female)
1/4 O.D. Tube Sample
Inlet Fitting
+ -
Chamber O-ring (in top of
chamber)