UNIDATA
Unidata Manual 6293 - Precision Water Level Instruments Issue 2.1
ii
6.4 F
LOATWELL
D
ESIGN FOR
W
ATER
L
EVEL
M
EASUREMENT
......................................... 25
6.5 M
EASURING
R
AINFALL
............................................................................................. 25
6.6 M
EASURING
P
AN
E
VAPORATION
............................................................................... 26
6.7 F
LOATWELL
D
ESIGN FOR
W
ATER
L
EVEL
M
EASUREMENT
......................................... 26
6.8 S
OURCES OF
E
RROR IN
F
LOAT
S
YSTEMS
................................................................... 26
6.9 C
AUSES OF
E
RROR
.................................................................................................... 27
7
SPECIFICATIONS: MODEL 6541 INSTRUMENT ................................................. 28
8
APPENDIX A - 6541L MICROLOGGER................................................................... 29
8.1 S
PECIFICATIONS
........................................................................................................ 29
8.2 M
OUNTING
................................................................................................................ 29
8.3 S
IGNAL
C
ONNECTIONS
.............................................................................................. 30
8.4 O
THER
C
ONNECTORS
................................................................................................ 31
8.5 T
HE
U
SER
P
OWER
S
UPPLY
(UPS).............................................................................. 31
8.6 R
EGISTER
A
LLOCATION
............................................................................................ 32
8.7 F
IELD
I
NSTALLATION
................................................................................................ 33
8.8 6541S/B
4-20
M
A
O
PTION
......................................................................................... 33
9
APPENDIX B - DETAILS OF UNIDATA FLOAT SYSTEMS ................................ 34
9.1 F
LOAT LINES
............................................................................................................. 34
9.2 F
LOATS
..................................................................................................................... 34
9.3 F
LOAT
P
ULLEYS
........................................................................................................ 37
9.4 F
LOAT
S
YSTEM
A
CCESSORIES
................................................................................... 37
10
APPENDIX C - FLOAT SYSTEMS............................................................................. 38
10.1 I
NTRODUCTION TO
F
LOAT
S
YSTEMS
.......................................................................... 38
10.2 S
OURCES OF
E
RROR IN
F
LOAT
S
YSTEMS
................................................................... 38
10.3 C
AUSES OF
E
RROR
.................................................................................................... 38
10.3.1
Float Line Shift................................................................................................. 39
10.3.2
Submergence of Counterweight ....................................................................... 39
10.3.3
Instrument Lag ................................................................................................. 39
10.3.4
Temperature Change........................................................................................ 40
10.3.5
Coefficients of Expansion................................................................................. 40
10.3.6
Correction Formulae........................................................................................ 40
10.3.7
Example ............................................................................................................ 41
10.4 R
EDUCING
E
RRORS
................................................................................................... 41
11
APPENDIX D – FLOATWELLS ................................................................................. 42
11.1 T
HE
N
EED FOR
F
LOATWELLS
.................................................................................... 42
11.2 F
LOATWELL
D
ESIGN
................................................................................................. 42
11.3 M
OUNTING THE
I
NSTRUMENT ON A
F
LOATWELL
....................................................... 43
11.4 M
EASURING
L
OCATION
............................................................................................. 43
11.4.1
Water Velocity .................................................................................................. 43
11.4.2
Siltation ............................................................................................................ 44
11.4.3
Environmental impact ...................................................................................... 44
11.4.4
Access and Security .......................................................................................... 45
11.5 O
THER
F
EATURES OF A
F
LOATWELL
S
ITE
................................................................. 45
