APLISENS Sp. z o.o., ul. Morelowa 7

, tel. [phone]

fax [phone], www.aplisens.com.pl, e-mail: aplisens@

.com.pl

, 03-192 Warszawa

aplisens

Version II/2002

SG-25 and SG-16 type

hydrostatic level probes

SG-25

SG-16

ü Any measurement range

from 2 up to 500 m H

2

O

ü Integrated internal circuit offering excess

voltage protection

ü Exi

a

I/IICT6 spark proof

Application

The SG-25 hydrostatic level probe is designed to meas-

ure liquid levels in tanks, wells or piezometers.
The SG-16 probe is a specialized device designed to

measure water levels in narrow diameter piezometers or

wells.

Principle of operation, construction

The probe measures liquid levels based on a simple

relationship between the height of the column of liquid

and the resulting hydrostatic pressure. The pressure

measurement is made at the level of the separating dia-

phragm of the submerged probe and is related to atmos-

pheric pressure via a capillary in the cable.
The active sensing element is a piezoresistive silicon

sensor separated from the medium by an isolating dia-

phragm. The sensor works in combination with an elec-

tronic amplifier, which supplies a standardized signal and

is equipped with a safety circuit protecting the probe from

excess voltage damage induced by atmospheric dis-

charge or by the power supply devices.

Assembly, operation

Released at the reference level, the probe can hang freely

on the cable or lie on the bottom of the tank. The cable

with capillary can be extended, using a standard signal-

ling cable. The cable connection should be contained in a

non-airtight box (internal pressure equal to atmospheric),

which prevents ingress of water or other contaminants

into the capillary. Where long signal transmission lines

are used, we recommend the use of an additional

Aplisens UZ-2 circuit to protect against excess voltage, in

the form of a wall box enabling cable connection. During

winding the minimum diameter of the wound cable should

be 30 cm, and the cable should be protected from physi-

cal damage. The leads at the end of the cable are con-

nected by a diode, which shorts out when the voltage

exceeds the permitted limit (39 V). For this reason the

cable supplied should not be shortened.
In tanks in which turbulence is possible (where mixers are

operating or where there is a turbulent inflow), the probe

should be mounted in a shielding tube (e.g. PCV). When

the probe is released to below 100 m the cable should be

suspended from a steel support. The isolating diaphragm

of the probe must not be cleaned mechanically.

∅

16.3

170

∅

25

140

Capillary

Red

(+)

Black

(–)

Safety

diode

shield

Diaphragm level

Version II/2002

APLISENS Sp. z o.o., ul. Morelowa 7

, tel. [phone]

fax [phone], www.aplisens.com.pl, e-mail: aplisens@

.pl

, 03-192 Warszawa

aplisens.com

Technical data for the SG-25 level probe

Measurement range 2 ÷ 500 m H

2

O (we recommend the standard ranges: 4, 10, 20, 50, 100 m H

2

O)

Measurement Range

2 m H

2

O

4 m H

2

O

0...10 m H

2

O ÷ 500 m H

2

O

Overpressure Limit

(repeatable – without hysteresis)

3 × range

2 × range

Accuracy

0.4%

0.3%

0.2%

Thermal error of zero

Typical 0.3% / 10°C

max 0.4% / 10°C

Typical 0.2% / 10°C

max 0.3% / 10°C

Thermal error of span

Typical 0.3% / 10°C

max 0.4% / 10°C

Typical 0.2% / 10°C

max 0.3% / 10°C

Special version with increased accuracy: SG-25 level probe, measurement range 0...10 m H

2

O

Accuracy 0.1%;

Total error at 0...25°C 0.3%

Long-term stability

0.1% or 1 cm H

2

O for 1 year

Hysteresis, repeatability

0.05%

Thermal compensation range

0 ÷ 25°C – standard,

-10 ÷ 70°C – special version

Process temperature limit

-25 ÷ 50°C – for range > 20 m H

2

O,

-25 ÷ 75°C – for range

≤

20 m H

2

O,

-25 ÷ 50°C – for Exi

a

version

ATTENTION: Do not allow the liquid to freeze in the immediate vicinity of the probe

Technical data for the SG-16 level probe

Measurement ranges

10, 20, 50, 100 m H

2

O

Overpressure limit

2 × range

(repeatable – without hysteresis)
Accuracy

0.5%

Hysteresis, repeatability

0.05%

Thermal compensation range

0 ÷ 25°C

Process temperature limit

0 ÷ 50°C

Electrical parameters (applicable to both probes)

Output signal

4 ÷ 20 mA, two-wire transmission

Special version 0 ÷ 10 V three-wire transmission (SG-25 only)

Power supply

12 ÷ 30 V DC (Ex: max 28 V)

15 ÷ 30 V DC (for 0 ÷ 10 V output)

Error due to power supply variation 0.005% / V

Load resistance

(for current output)

sup

R [

U

V] 12 V

0.02 A

Ω

]

[

≤

−

Construction material of case and isolating diaphragm (applicable to both probes) 00H17N14M2 (316Lss)

Cable shield (applicable to both probes) POLYURETHANE
Special features, certificates (not applicable to SG-16)

◊

Ex – spark-proof

◊

-10 ÷ 70°C – extended thermal compensation range

◊

0 ÷ 10 V – output voltage (not applicable to Ex)

◊

For other features phone us on: [phone]

SG-25 /___/___/ L = ... m

Special features:

Ex, -10 ÷ 70°C, 0 ÷ 10 V,

others (description)

Cable length

Example 1: SG-25 level probe / Ex version, extended temperature compensation range / measurement range 0 ÷ 2.5 m of

fuel oil with density = 0.83 g/cm / cable length 6 m

ñ

3

SG-25 / Ex, -10 ÷ 70°C / 0 ÷ 2.5 m ( = 0.83) / L = 6 m

ñ

Example 2: SG-16 level probe / measurement range 0 ÷ 20 m of water / cable length 50 m

SG-16 / 0 ÷ 20 m H O / L = 50 m

2

Measurement range

Ordering procedure

Cable length

Measurement range

(standard only)

SG-16 /___/ L = ... m