Dwyer GFM4 - Manual (Page 16)

9.3 - Technical Assistance
Dwyer
® Instruments, Inc. will provide technical assistance over the phone to
qualified repair personnel. Please call our Technical Assistance at 219-879-8000.
Please have your Serial Number and Model Number ready when you call.
10. CALIBRATION CONVERSIONS FROM REFERENCE GASES
The calibration conversion incorporates the K factor. The K factor is derived from
gas density and coefficient of specific heat. For diatomic gases:
Note in the above relationship that d and Cp are usually chosen at standard
conditions of one atmosphere and 25°C.
If the flow range of a Mass Flow Controller or Controller remains unchanged, a
relative K factor is used to relate the calibration of the actual gas to the reference
gas.
For example, if we want to know the flow rate of oxygen and wish to calibrate
with nitrogen at 1000 SCCM, the flow rate of oxygen is:
QO = Qa = Qr x K = 1000 X 0.9926 = 992.6 sccm
where K = relative K factor to reference gas (oxygen to nitrogen)
1
d X Cp
where d = gas density (gram/liter)
Cp = coefficient of specific heat (cal/gram)
= Kgas
Qa Ka
Qr Kr
where Qa = mass flow rate of an actual gas
(sccm)
Qr = mass flow rate of a reference gas
(sccm)
Ka = K factor of an actual gas
Kr = K factor of a reference gas
= K =
2
APPENDIX I
Dwyer ® GFM3/4 EEPROM Variables Rev. A3
Gas Independent Variables
Indication
BlankEEPROM
SerialNumber
ModelNumber
SoftwareVer
TimeSinceCalHr
Options1
Reserved2
AddressRS485
DogGasNumber
FlowUnits
AlarmMode
LowAlarmPFS
HiAlarmPFS
AlmDelay
RelaySetting[0]
RelaySetting[1]
TotalMode
Total
TotalFlowStart
TotalVolStop
KfactorIndex
UserDefKfactor
UDUnitKfactor
UDUnitTimeBase
UDUnitDensity
TPUnits
FlowOutScaleV
FlowOutScale_mA
FlowOutOffset_mA
TempOutScaleV
TempOutScale_mA
TempOutOffset_mA
PresOutScaleV
PresOutScale_mA
PresOutOffset_mA
TAInScaleV
TAInOffsetV
PAInScaleV
PAInOffsetV
SensorZero
Klag [0]
Klag [1]
Klag [2]
Klag [3]
Klag [4]
Klag [5]
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Kgain [0]
Kgain [1] No.
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53 Data Type
char[10]
char[20]
char[20]
char[10]
float
uint
char
char [3]
int
int
char
float
float
uint
char
char
char
float
float
float
int
float
float
int
char
char
float
float
float
float
float
float
float
float
float
float
float
float
float
float
float
float
float
float
float
float
float
float
float
float
float
float
float
float Notes
Do not modify. Table Revision.
Serial Number
Model Number
Firmware Version
Time since last calibration in hours
Misc. Options*
Flow Conditions [0-STD, 1-ACTUAL]
Two character adress for RS485
Current Gas Table Number [0 - 9]
Current Units of Measure [0 - 10]
Alarm Mode [‘R’ - Enabled, ‘S’ - Disabled]
Low Flow Alarm Setting [%FS] 0 - Disabled
High Flow Alarm Setting [%FS] 0 - Disabled
Flow Alarm Action Delay [0 - 3600 sec] 0 - Disabled
Relay #1 Assignment Setting (N, T, H, L, Range)
Relay #2 Assignment Setting (N, T, H, L, Range)
Totalizer Mode [‘R’ - Enabled, ‘S’ - Disabled]
Totalizer Volume in %*s (updated every 6 min)
Start Totalizer at Flow [%FS] 0 - Disabled
Totalizer Action Limit Volume [%*s] 0 - Disabled
Internal K-Factor Index [0 - 31]**
User Defined K-Factor
K-Factor for User Defined Units of Measure
User Defined Unit Time Base [1, 60, 3600 sec]
User Defined Unit Density Flag [Y, N]
Temperature/Pressure Units [C (Bar), F (PSI)]
DAC 0 to 5/0 to 10 Analog Output Scale for Flow
DAC 4 to 20 mA Analog Output Scale for Flow
DAC 4 to 20 mA Analog Output Scale for Flow
DAC 0 to 5/0 to 10 Analog Output Scale for Temp.
DAC 4 to 20 mA Analog Output Scale for Temp.
DAC 4 to 20 mA Analog Output Scale for Temp.
DAC 0 to 5/0 to 10 Analog Output Scale for Pressure
DAC 4 to 20 mA Analog Output Scale for Pressure
DAC 4 to 20 mA Analog Output Scale for Pressure
ADC Temp. Analog In Scale (0 to 5 V)
ADC Temp. Analog In Offset (0 to 5 V)
ADC Pressure Analog In Scale (0 to 5 V)
ADC Pressure Analog In Offset (0 to 5 V)
D/A Value for Sensor Zero [0 to 4095 counts]
DRC Lag Constant [Do Not Alter]
DRC Lag Constant [Do Not Alter]
DRC Lag Constant [Do Not Alter]
DRC Lag Constant [Do Not Alter]
DRC Lag Constant [Do Not Alter]
DRC Lag Constant [Do Not Alter]
Gain for DRC Lag Constant [Do Not Alter]
Gain for DRC Lag Constant [Do Not Alter]
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