21
Adjusting for Specific Gravity
If the working fluid is not water, you
can specify the fluid’s specific grav-
ity. Select the
SG
option from the
menus.
Key in the specific gravity and press
ENTER
. Use a value of 1 when work-
ing with water.
The display returns to the transducer
menus.
The intermediate transducer pressure is converted to a head value
as follows:
H = P
×
U / SG
where
H =
Head in feet
P =
Pressure in PSI
U =
2.30667 feet of water/PSI
SG =
Specific gravity (fluid density/water density)
Entering the Orifice Coefficient
Select the
KxA
option from the trans-
ducer menu.
Key in your computed value of KxA
and press
ENTER
.
The display will return to the trans-
ducer menu.
Use the following procedure to compute the value of the orifice coef-
ficient (KxA) as used in the HERMIT 2000:
1. Compute the ratio R as the diameter of the orifice divided by the
inside diameter of the pipe. You can use any convenient units of
measure as long as both diameters are in the same units.
2. Use the computed value of R and the curve below to determine
the value of K.
3. Compute the area A of the orifice in square inches (
p
d
2
/4).
4. Compute the product KxA and enter this value into the instru-
ment. The resulting flow will be in gallons per minute (GPM).
Other units of flow can be obtained by multiplying KxA by the ap-
propriate conversion factor before entering it into the HERMIT 2000.
Orifice flow is computed as:
Q = KxA (27.7874)
Ö
H
where
Q =
Volumetric flow rate in GPM
K =
Orifice coefficient from curve
A =
Orifice area in square inches
H =
Transducer head in feet
Flow Setup Procedure
You can use the following procedure to properly set up a pressure
transducer with a flow type input channel.
1. Program the transducer parameters of linearity, scale factor, and
offset. Remember to set to zero any parameter not specified.
2. Program the transducer warmup delay. Set it to 50 mSEC if not
specified otherwise.
3. Enter the specific gravity. Make certain it has been set to 1 if you
are working with water.
4. Compute and enter the orifice coefficient KxA.
5. Connect the transducer to the discharge pipe and make all cable
connections to the HERMIT 2000.
6. Use the
READ
option to check the
operation of the transducer.
If possible, generate flow prior to
a test to verify transducer opera-
tion, and that all parameters have
been entered correctly.
Programming Dual Types
The dual type input allows you to interface with one of In-Situ’s
unique dual parameter transducers such as conductivity/tempera-
ture or pH/temperature. These transducers permit the measurement
of temperature and a temperature-dependent parameter with a single
input channel.
The parameters for a dual type input
are presented in a single menu.
Press
F3
to select the
COEF
. option.
Key in each coefficient (0-9), press-
ing
ENTER
after each entry.
Section 5: Setting Up Transducers
SG [1]?
_
Input 3: Flow
DELAY SG
Input 3: Flow
DELAY SG
Input 3: Flow
READ I.D. KxA more
Input 3: Flow
READ I.D. KxA more
KxA [0]?
_
Input 3: Flow
READ I.D. KxA more
Input 3: Flow
25.760
Input 4: Dual
READ I.D. COEF.
Coef. 0 [4]?
_