The impact of urban groundwater upon surface water - eTheses ...

E
>10
VDC
L
TS
R
E
L
Surface
(L1)
T S
T
(E) (C)
(B)
1 2 5
Figure 4.5 Pressure Logging System
5 10
vent tube
5 core cable
10 9 6
EBC 3 2 1
2
V
S
9
Down Hole
Component Connections
P
3 1
2
Plastic body form +
Heat shrink
V.A
V
1
3
Poly eurethane
potting compound
4 3 2 1
E - DC power supply > 10 VDC [in this case 2 x 9V DC batteries in series ]
L - Data logger [ Gemini Tiny Talk (8 bit) voltage input,0-2.5 VDC ( RS#TK-0702)* 1 ,
resolution 10 mv]L1 – trigger output
Or [ ERTCO Volt101 (16 bit), 0-15 VDC ,no trigger (CP#U-38010-25)* 2 , resolution
0.5 mv]
T - Darlington small signal transistor [(RS#157-7157)] Gemini logger only
S - Relay [Omron G5V-1, 5 VDC (RS#369-343)]
V - Voltage Regulator 10 V [(RS#298-7151)]
P - Pressure Transducer 0-5 psi [gauge, compensated, 0-50mv, (RS#286-6580]
A - Amplifier [Burr-Brown, single supply micro power instrumentation amplifier
(RS#285-8126)]
R – Resistor to set the gain [Gain = 5+ 200k/R, used 4.7k but this may be altered for
greater sensitivity of measurements over a smaller range.]
*1 Radio Spares UK catalogue number * 2 Cole Palmer UK catalogue number
Components V,P,A are located downhole. For this system a range of 3.3m provides a
resolution of 1 cm with the Gemini and 1 mm with the ERTCO (however the ERTCO has
no trigger system requiring power to be on all the time). With a total component price of
£100 the whole system can be constructed to fit a 20 mm ID piezometer and be concealed
within a 13x13 cm stop cock cover
P
P
A
2
4
3
2
1
2
3
4
A
5
4
7
1
8
8
7
6
5
6
15mm
R