Level pressure sensing
transmitter type 681
Pressure range
0 ... 0.1 – 25 bar

The pressure transmitters of type 681 with piezoresistive
measuring elements have compensated, calibrated and amplified sensor signals which are available as standard voltage orcurrent outputs.
In the immersion-sensor version with a salt water and oilresistant connection cable they are specially suited for levelmeasurement, even in the presence of corrosive liquids.
The cable incorporates a tube for compensation of the ambientpressure.
Manufactured from stainless steel, its welded construction
provides a watertight seal.

• Mechanically protected diaphragm due
to special head design• Supplementary weight (option) improves
stabilization of sensor in turbulent media• Effective overload protection due tochemically etched chip diaphragm andspecially designed glass gland• Compact construction using SMD technology,enhances operational reliability in the presenceof shock and vibration• Welded construction provides 100%
sealing against media

Huba Control type 681 - Technical data subject to change - Edition 11/2019

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Technical overview
Pressure ranges 1)
RelativeAbsolute

0 ... 25 bar
optional available

Overload
3x pressure range, min. 3 bar
Rupture pressure> 200 bar
MediumPermissible medium

according order code selection table (other medium on request)

Material
Stainless steel 1.4435 (316L)
TitaniumFPM (other at request)
PUR, PE oder teflon

Diaphragm, case
Sealing material
Cable
Temperature 2)
Medium temperature
Output and power supply-5 ... +80 ÀC
output0 ... 5 V
0 ... 10 V
4 ... 20 mA
4 ... 20 mA

power supply
12 ... 30 VDC
12 ... 30 VDC
9 ... 33 VDC
9 ... 28 VDC

permissible load 5)> 10 kOhm> 10 kOhm
supply voltage - 9V
[Ohm] max.
0.02 Asupply voltage - 9V
[Ohm] max.
0.02 A

Ex-version
Ex-Admission
Standardsgas
II 1G Ex ia IIB/IIC T3 ... T6EN 60079-0 / EN 60079-11

dust
II 1D Ex iaD 20 IP6x T145 ... T70 ÀCEN 61241-0 / EN 61241-11

Temperature class Ex-version
Medium temperature

T6-5 ... +50 ÀC

T4-5 ... +80 ÀC3) 4)

3 wire2 wire2 wire (Ex)Electrical connection
Cable
Tests / Admissions
Mechanical load
Interference emitInterference resitance

PUR, PE or teflon (In variable lengths)norm
EN 60068-2-6
EN 60068-2-27
EN 55022
EN 61000-4-2
EN 61000-4-3
EN 61000-4-4
EN 61000-4-5
EN 61000-4-6

charactervibration
shock
emitted interference, class B
discharge static electricity
electromagnetic radiation
fast transients (burst)
impulse voltage (surge)
grid-bound electromagnetic blockage

level
10 g (4 ... 2000 Hz, oscillation μ 10 mmpp)
100 g (pulse duration 6 ms)< 30 dBøV/m (0.03 ... 1 GHz)
8 kV contact-, 15 kV air discharge
10 V/m, 0.08 ... 2.7 GHz, 80% AM 1 kHz, 3 s
4 kV
Line-Line 0.5 kV/42 Ohm, Line-Earth 1 kV/42 Ohm
10 V, 0.15 ... 80 MHz, 80% AM 1 kHz, 3 sPackaging
Single packaging

carton padded cellular material

WeightWithout supplementary weight (without cable)
With supplementary weight (without cable)
Cable~ 145 g
~ 405 g~ 50 g/m

Accuracy
total error band (*) [μ%fs] per pressure ranges [bar]0.1 ... 0.5> 0.5 ... 2> 2 ... 25
Characteristic line deviation [μ%fs] 0.25 oder 0.1(typ./ max.) -5 ... +50 ÀC(typ./ max.) -5 ... +80 ÀCCharacteristic line deviation [μ%fs] 0.05(typ. / max.) -5 ... +50 ÀC(typ. / max.) -5 ... +80 ÀC

0.7 / 1.0
1.0 / 1.5

0.7 / 1.0
1.0 / 1.5––

0.3 / 0.5
0.75 / 1.0

0.3 / 0.5
0.75 / 1.0(*)

total error band incl. charactersistic line deviation, temperature error zero point and operating range, hysteresis and repeatability at max. signal range.

1)

See order code selection table. Other on request.
Influence from the supply voltage types < 0.05% fs4)

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1.0 / 1.5
2.0 / 2.52)
5)

Compensated temperature range see order code selection table
Influence permissable load < 0.05% fs3)

Short circuit proof with polarity reversal protection

Huba Control type 681 - Technical data subject to change - Edition 11/2019

1Order code selection table

681.

2

345678910X X X X X X X X X X

Cable
Case
Fig. 1, 2, 3, 4
Diesel oil / fuel oil / kerosene
teflonstainless steel
Fig. 1, 2
Salt water / brackish water
PUR
Titan
Medium 1)
Fig. 1, 2, 3, 4
Drinking water, potablePE
stainless steel
Fig. 1, 2, 3, 4Lake water / river water
PUR
stainless steel
Fig. 1, 2, 3, 4Benzene
teflonstainless steel
Fig. 1, 2
Chlorinated water
PUR
Titan
0 ... 100 mbar
0 ... 160 mbar
0 ... 250 mbar
0 ... 400 mbar
0 ... 600 mbar
0 ... 1bar
Pressure range 2)
0 ... 1.6 bar
0 ... 2.5 bar
0 ... 4bar
0 ... 6bar
0 ... 10bar
0 ... 16bar
0 ... 25bar
0 ... 5 V
12 ... 30 VDC
0 ... 10 V
12 ... 30 VDC
Output / power supply
4 ... 20 mA
9 ... 33 VDC
4 ... 20 mA
9 ... 28 VDC
overvoltage protection 3)< μ0.25% fs
Characteristic line deviation < μ0.10% fs< μ0.05% fs (> 0.5 ... 25 bar)
-5 ... +50 ÀC compensated, medium temperature permissible: -5 ... +50 ÀC-5 ... +80 ÀC compensated, medium temperature permissible: -5 ... +80 ÀC
Temperature range 4)
Ex T6 (Ta: -5 ... +50 ÀC) -5 ... +50 ÀC compensated (medium temperature permissible: -5 ... +50 ÀC)
Ex T4 (Ta: -5 ... +80 ÀC) -5 ... +80 ÀC compensated (medium temperature permissible: -5 ... +80 ÀC)
Cable length
Data in meters
Example: 2 0 )Fig. 1closed, short caseFig. 1closed, with supplementary weight 5)
Construction
Fig. 2
open, short caseFig. 2
open, with supplementary weight 5)
Version0123450000000000111012345678
90
120
1
3
4

3,40,2,40,2,4

12
30
1230
123N

± 5 teflon-cable± 6 PE-/PUR-cable± 24± 24(4x) 4

Dimensions in mm / Electrical connections

AFig. 1 closed(mm)without supplementary weightwith supplementary weight1)
4)

A (mm)

B8817584171

colour2-wire

3-wirewhiteyellowbrown

INOUTINGNDOUT

Other medium on request
For medium temperatur > 50ÀC, PE or Teflon cable must be used2)
5)

Other pressure ranges on request
Not available with titan case

Huba Control type 681 - Technical data subject to change - Edition 11/2019

BFig. 2 open3)

II 1G Ex ia IIB/IIC T3...T6 / II 1D Ex iaD 20 IP6x T145...T70 ÀC3/4

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Huba Control type 681 - Technical data subject to change - Edition 11/2019