Sensidyne gilian gilibrator 2 Operation & Service Manual - Introduction
— PRELIMINARY —
GILIAN GILIBRATOR 2 CALIBRATION SYSTEM
8
Sensidyne Document No. 850190M (Rev G)
SECTION ONE
INTRODUCTION
1.1
OVERVIEW
The Gilian Gilibrator 2 Calibration System is an easy to
use Primary Standard for the calibration of air sampling
equipment. The system includes a high accuracy, elec-
tronic flowmeter that provides instantaneous air flow
readings and cumulative averaging of multiple samples.
Three Wet Cell Assemblies and one Piston Cell Assem-
bly provide a wide range of flow rates and are easily in-
terchangeable using twist-on/off mounting.
A crystal controlled microprocessor Control Unit is de-
signed for accurate data readings. A dual function
DELETE/RESET
button on the Control Unit subtracts er-
roneous readings to ensure accurate data, or can can-
cel the current readings completely.
A printer interface on the Control Unit allows you to
output the sampling results to a printer or PC com-
puter. Windows™ compatible Gilibrator 2 Flow Moni-
toring Software is available that allows you to collect,
store, and plot flow samples.
Features of the Gilibrator 2 Calibration System include
an easy-to-read display; simultaneous display of flow
rate, flow average, and number of samples taken; dis-
play indicators for LOW BAT, WAIT, ERROR 1, and
ERROR 2; and automatic power shutoff when the unit
is inactive for 15 minutes. You can also specify the
number of samples to be taken (5 to 95) in 5 sample
increments.
Gilibrator 2 Calibration System Kits include either a
Wet or Piston Cell Assembly, Control Unit Base (either
CE or non-CE approved), Battery Charger, Tubing, and
Soap Solution & Dispenser (Wet Cells only). A 15-to-9
pin adapter is included with the non-CE Control Base
to allow it to operate with existing 9-pin Wet Cell As-
semblies.
Interchangeable Flow Cell Assemblies are available as
follows:
•
Piston Cell (1 to 5 LPM)
•
Low Flow Wet Cell (1 to 250 cc/m)
•
Standard Flow Wet Cell (20 cc/m to 6 LPM)
•
High Flow Wet Cell (2 to 30 LPM)
1.2
THEORY OF OPERATION
To be a primary standard, all values must be absolute
and measured as absolute. A primary standard airflow
measurement is a volume divided by a time interval as
performed by the Control Unit of the Gilibrator 2. The
volume (V) is measured volume of space between
two infrared sensors. The time (t) is that interval
needed for an object (soap film bubble or piston cell
piston) to travel between the two sensors which
bound the volume. Thus, the volume per unit of time
(V/t) becomes the flow rate. Because the electronic
clock is far more accurate than the volume measure-
ments, the volume measurement accuracy determines
the overall accuracy of the unit.
The Gilibrator 2 consists of two elements, the Flow
Cell Assembly (either Wet or Piston ) and the Control
Unit Base. The function of the Flow Cell Assembly is
to provide a means for measuring an object (soap film
bubble or piston cell piston) traveling up a flow tube
through a known volume of space.
Measurement of the travel time is done by means of
“top” and “bottom” infrared sensor pairs mounted
along the flow tube. The volume bound by these sen-
sors is set accurately to a primary volume standard.
As the object (bubble or piston) moves up the tube, it
trips the bottom sensor pair. As it moves further up
the tube, it trips the top sensor pair. The time differ-
ence between the bottom and top sensors becomes
the elapsed travel time. This timing information (along
with the volume information) is sent to the micropro-
cessor in the Control Unit Base. The calculated flow
and sample information are then displayed directly on
the Liquid Crystal Display.