Instruction Manual
Tek-LCD 7801C
www.tek-trol.com
Technology Solutions
45
Table 2: Programmable Exponent for Open Channel Flow
Function
Desire
Programming
Open Channel Flow
3" Parshall flume
Use Scale Exponent Function
; Set
e
xponent to 1.547
Flow Rate 1
Millions of Gallons per Day
(MGD)
Set 4 mA: 0; Set 20 mA: 3.508;
Custom unit: MG; Time base: day
Flow rate units: MG/day
Total 1
Millions of Gallons
Input: Flow Rate 1 Select unit = MG
Sampling Channel 2
Take a 1 pint sample every
100,000 gallons
Input: Total 1;
Function: Sampler
;
Sample Interval: 0.1 MG Sample
Time: 10 sec
Sampling Relay 1
Turn valve on to take a
sample
Input: Channel 2 (On / Off)
; Use a
timer to count the time needed to
take the sample
Total 2 Non-Resettable Program controller so total
2 can never be reset
Input:
Flow Rate 1
; Set total 2 as
non-resettable total
Screen
Display flow rate, totals,
and relay status
Set a screen to display rate, total 1,
total 2, and relay status.
6.16.2
Specific Weir or Flume Function
•
In this method, the user selects one of the following functions to be applied to the input
from a menu in the Tek-
LCD 7801C: Parshall Flumes, V
-Notch Weirs, Cipolletti Weirs,
Rectangular Weirs with or without Contractions.
•
The second table on the right shows the parameters the user then enters. In addition, a
total can be setup as non-resettable, and a relay can be programmed to take a sample at
user-defined intervals.
Table 3: Specific Weir or Flume Function for Open Channel Flow
Function
Desire
Programming
Open Channel Flow
3" Parshall flume
Create Channel 1 to measure head
height;
4mA = 0 ft
;
20mA = 3ft
Flow Rate 1
Millions of Gallons per
Day (MGD)
Create Channel 2 for flow rate;
Use Flow
–
Parshall Flumes function Constant K =
0.992;
Head =
Channel 1 head height
Custom unit: MG; Time base: day
Total 1
Millions of Gallons
Input: Flow Rate 1 Select unit = MG
Sampling Channel 2 Take a 1 pint sample
every 100,000 gallons
Input: Total 1 Function: Sampler
Sample Interval: 0.1 MG Sample Time: 10
sec
Sampling Relay 1
Turn valve on to take a
sample
Input: Channel 2 (On / Off)
Use a timer to count the time needed to
take the sample
