EB 7575 EN
Translation of original instructions

Fixed sensor

Sensor with capillary tube

Type 3812 Pneumatic Transmitter for Temperature
Pneumatic Transmitters

Edition February 2020

Note on these mounting and operating instructions
These mounting and operating instructions assist you in mounting and operating the device
safely. The instructions are binding for handling SAMSON devices.
Î For the safe and proper use of these instructions, read them carefully and keep them forlater reference.
Î If you have any questions about these instructions, contact SAMSON‘s After-sales Service(aftersalesservice@samsongroup.com).

The mounting and operating instructions for the devices are included in
the scope of delivery. The latest documentation is available on our website
at www.samsongroup.com > Downloads > Documentation.

Definition of signal words! DANGER
Hazardous situations which, if not avoided,
will result in death or serious injury! WARNING
Hazardous situations which, if not avoided,
could result in death or serious injury

2! NOTICE
Property damage message or malfunction
NoteAdditional information
Tip
Recommended action

EB 7575 ENContents

1General safety instructions..............................................................................42

Process medium and scope of application........................................................52.1

Transportation and storage..............................................................................53

Design and principle of operation...................................................................64Installation.....................................................................................................74.1

Version with fixed bulb sensor..........................................................................74.2

Version with capillary sensor...........................................................................74.3

Capillary tube................................................................................................74.4

Installing the sensor.........................................................................................74.5

Pneumatic connections....................................................................................75Operation......................................................................................................85.1

Zero point calibration......................................................................................86Versions.........................................................................................................97

Technical data..............................................................................................108

Dimensions..................................................................................................118.1

Accessories..................................................................................................12EB 7575 EN3

General safety instructions!

1 General safety instructions− The device must be mounted, started up or serviced by fully trained andqualified personnel only; the accepted industry codes and practices are tobe observed. Make sure employees or third parties are not exposed to anydanger.
− According to these mounting and operating instructions, trained personnel
refers to individuals who are able to judge the work they are assigned toand recognize possible dangers due to their specialized training, theirknowledge and experience as well as their knowledge of the applicablestandards.
− To ensure appropriate use, only use the device in applications where the operating pressure and temperatures do not exceed the specifications used forsizing the device at the ordering stage.
− The manufacturer does not assume any responsibility for damage caused byexternal forces or any other external factors.
− Any hazards that could be caused in the regulator by the process medium,operating pressure or by moving parts are to be prevented by taking appropriate precautions.
− Proper transport, storage, installation, operation, and maintenance are assumed.
− SAMSON does not assume any liability for damage caused when the device
is not used as intended.

4EB 7575 ENProcess medium and scope of application

2 Process medium and scope of application
Instrument for use in pneumatic control systems for measuring temperatures and converting
the measured value into a standardized pneumatic signal from 0.2 to 1.0 bar or 3 to 15 psi
Suitable for liquids, gases or vapors at temperatures from –40 to +300 °C.

2.1 Transportation and storage
Transport and store within permissible ambient temperature range (–40 to +90°C). Protect
the transmitter against adverse influences, such as shocks, dirt or moisture.

EB 7575 EN5Design and principle of operation3 Design and principle of operation
The sensor of the transmitter is either fixed tothe transmitter or connected with the measuring system over a capillary tube, dependingon the version.
The medium temperature creates a pressure
proportional to the temperature in the gasfilled sensor (1.1). This pressure acts on themeasuring bellows (1.3) creating a force,
which is measured at the balance beam (3)and converted into a pneumatic signal (pA).

Temperature measuringsystem
1.1 Sensor
1.2 Capillary tube
1.3 Measuring bellows
2 Base plate
1345678The supply air pZ flows through the booster(8), passes on to the restriction (9) and thenozzle (7) and finally hits the flapper (6).
An increase in temperature causes theflapper to come closer to the nozzle. As aresult, the output pressure pA applied to thefeedback bellows (5) rises until a new
equilibrium is reached, i.e. until the output
signal reaches a value proportional to thetemperature.
Zero is adjusted at the adjustment screw(11).

Balance beam
Cross spring pivot
Feedback bellows
Flapper plateNozzle
Booster

9 Restrictor10 Damping
11 Zero adjustment screw
pZ Supply airpA Output pressure

Fig. 1: Functional diagram

6

EB 7575 EN

Installation

4 Installation

4.3 Capillary tube

See section 8 on page 11.

Route the capillary tube ensuring that it does
not get damaged. The smallest bending radius must not be smaller than 50 mm.

4.1 Version with fixed bulb
sensor
Install the transmitters in such a way that thetemperature sensor (1.1) is in the horizontal
position and the pneumatic connections facedownwards.
If a different mounting position is used, thelower measuring range value might be shifted.
Readjust zero using the zero adjustment
screw (11) as described in Chapter 5.1. The
measuring span remains unaffected by a different mounting position.
Regardless of which mounting position isused, the bulb sensor with its effective lengthof 300 mm must be completely immersed in
the process medium that is to be measured.

4.2 Version with capillary
sensorA bracket is supplied to mount the transmitter to mount to a wall. Mount the device ashorizontal as possible with the pneumaticconnections at the side.
Pipe mounting requires a special mounting
bracket (order no. 1089-0101).
The temperature sensor can be installed inany position as required. The bulb sensor
with its effective length of 300 mm must becompletely immersed in the process mediumthat is to be measured.

EB 7575 EN

Any capillary tube that is not used must berolled up. Do not bend or shorten it.
The capillary tube must not be exposed to
any large temperature fluctuations.

4.4 Installing the sensor
To install the sensor, a coupling sleeve withR ½ or R ¾ female thread must be used at
the point of measurement depending on thesensor version. Screw or seal one of themounting parts shown in Fig. 3 into thissleeve.
The mounting parts for the sensor must beordered separately. They are not included in
the scope of the transmitter delivery.

4.5 Pneumatic connections
The pneumatic connections are designed asa bore with 1/8 NPT (G 1/8) thread.
Conventional screw fittings for pipes or plastic hoses may be used.
Note
The supply air is dry as well as free of oil
and dust. Read the maintenance instructions
for upstream pressure reducing stations.
Blow through all air pipes and hoses thoroughly before connecting them.

7

Operation

5 Operation
The measuring range specified in the order(see nameplate) is already set at the factoryand cannot be changed.
Depending on the mounting position though,zero (lower range value) can be readjusted.

5.1 Zero point calibration
1. Remove the cover from the transmitter.
2. Connect a pressure gauge at the pneumatic output and apply a supply air of
1.4 ± 0.1 bar to the supply air input.
3. Produce a temperature at the temperature sensor that corresponds with thelower range value of the transmitter, e.g.
50 °C at a measuring range of +50 to+150 °C.
4. Set the supply air. The pressure gaugemust indicate a pressure of 0.2 bar. If
this value is incorrect, readjust the zeroadjustment screw (11) accordingly.

8

EB 7575 ENVersions6 Versions
The transmitter is configured according to the specified order number.
VersionOrder no.: 3812-xxxxxx

xx

000x

Sensor type
Bulb sensor

1Air sensor

2Sensor for food processing (T-union)

3Sensor version
Capillary tube, 3 m

1

Protected capillary tube, 3 m

2Capillary tube, 6 m

3Protected capillary tube, 6 m

4Bulb sensor, fixed

5Measuring span50 °C

00100 °C

10200 °C

11Output signal
0.2 to 1 bar

01

3 to 15 psi

0

2Connection
G 1/8
1/8NPT0

1

02

Measuring range1)–20 to +30 °C

10 to +50 °C

20 to +100 °C

3+50 to +150 °C

40 to +200 °C

5Span 50 °C, lower range value between –40 and +150 °C

6 1)Span 50 °C, lower range value between +150 and +250 °C

7 1)Span 100 °C, lower range value between –40 and +200 °C8 1)

Span 200 °C, lower range value between –40 and +100 °C

9 1)

Specify the measuring range that you require on ordering. The transmitter will then delivered with this measuringrange.

EB 7575 EN9Technical data

7 Technical data
Table 1: Technical data
Measuring span

50 °C

Measuring range limits
Overload limits

100 °C

200 °C–40 °C/+300 °C
350 °C

Supply air

350 °C

500 °C

Supply air 1.4 ±0.1 bar (20 ±1.5 psi)

Output

0.2 to 1.0 bar/3 to 15 psi
max. 2 mn3/h

Air output capacity
Consumption0.1 mn³/h in steady-state condition

Reversing error< 0.3 %

Deviation from terminal-based
linearity< 0.6 %

Hysteresis< 0.2 %

Influence

Supply air: < 0.12 %/0.1 bar

Pressure at the sensor< 0.4 %/10 bar

Ambient temperature< 0.06 %/K< 0.2 %/10 bar< 0.1 %/10 bar< 0.03 %/K

Permissible ambient temperature–40 to +90 °C

Capillary tube length

3 m or 6 m

Table 2: Materials · Material numbers according to DIN EN
Type 3812
Enclosure and cover
Bellows

Die-cast aluminum AlSi12Bronze

Bellows fixtureBrassDiaphragms

ECO (epichlorohydrine)

Seals and O-rings
SensorSensor filling

Silicone
Stainless steel 1.4571/1.4404
Inert gas

Capillary tube

Stainless steel 1.4571/1.4404

Clamping flange, screw gland,
thermowells

Stainless steel 1.4571/1.4404

10EB 7575 EN

Dimensions

8 Dimensions

143Ø12Standard version3001)
420

70
NPTG1/8

1/853
Ø17R¾1801)

For installation inT-union according toDIN 11857

Wall mounting

250356

Ø2082973001)

Ø7R¾Ø12425

4002712501801)320

Ø17R¾3052

NPTG1/81/8Special version withprotective metal hose
Air sensor

Installation inT-union according
to DIN 11857

Standard version

Pipe mounting

59

Pipe mounting
Order no.: 1089-0101

1)

Active sensor length

Fig. 2: Dimensions in mm

EB 7575 ENNPT
G1/8

1/8

OutputSupply air

11Dimensions

8.1 Accessories
Clamping flange
Clamping flange for wall mounting, e.g. onpressureless vessels, ducts etc.
Order no.: 1090-9547

Screw gland PN 10*) G ½: order no. 1080-4881
G ¾: order no. 1080-4882

Screw gland PN 40*) G ½: order no. 1080-4884
G ¾: order no. 1080-4885

Screw-in thermowell, CrNiMo steel, PN 63*) G ½: order no. 1080-4888
G ¾: order no. 1080-4889
Weld-in thermowell, CrNiMo steel, PN 63
Thermowell (CrNiMo steel) with flange DN 25(without image) for PN 40 or PN 100
Details on request
Weld-in version:
Order no.: 1080-4890
Flange:Order no.: 1080-4891 (PN 40)
Order no.: 1080-4892 (PN 100)
Fig. 3: Accessories

12EB 7575 EN

EB 7575 EN13

14EB 7575 EN

EB 7575 EN15

SAMSON AKTIENGESELLSCHAFT
Weismüllerstraße 3 · 60314 Frankfurt am Main, Germany
Phone: +49 69 4009-0 · Fax: +49 69 4009-1507
samson@samsongroup.com · www.samsongroup.com

2024-03-18 · English

EB 7575 EN