NEW GENERATION OF TORQUE TUBE

FST4000 Series

DISPLACER TYPE LEVEL TRANSMITTER

GENERAL

FST4000 is a torque tube displacement type level indicating transmit-

ter with intelligent data processing function. Through 18 years of field

proven experiences accumulated by the existing model FST-3000,

FST4000 has intensified its reliability by adding such features as SIL2

compatible functional safety, ATEX flameproof and field bus communi-

cation of FOUNDATION Fieldbus .

Varieties of materials and wide range of pressure ratings are available

to meet various applications such as high pressure and temperature

boilers as well as low temperature down to minus 196

℃ of liquefied

gases.

STANDARD SPECIFICATION

1）Detection method

：Torque tube type displacer

2）Measuring range

：Min. 0 to 300 mm, Max. 0 to 3000 mm

3）Liquid density

① Level measurement

：0.2 to 1.5 g/cm3

② Interface measurement ：Density difference between 2 liq-

uids is more than 0.1 g/cm3

③ Density measurement ：Min. density span is 0.2 g/cm3

Consult TOKYO KEISO Co. Ltd.

for the services not mentioned

above.

✽

Measurements ② and ③ cannot be performed accurately

unless the displacer is fully submerged in the liquid.

4）Available pressure class ：ASME class 150, 300, 600, 1500

and 2500

5）Fluid temperature range ：–196 to +450℃

6）Installation

：Tank top or tank side installation

7）Connection size

：External chamber type : 1-1/2 or

2 inch flange Internal chamber

type : 3 or 4 inch flange See

Fig.2 and Fig.3.

8）Ambient temperature

：–40 to +70℃ during operation

Allowable temperature is subject

to the applicable explosionproof

standards.

：–45 to +80℃ during storage

9）Ambient humidity

：0 to 95% R.H. during operation

：0 to 85%R.H. during storage

10）Available material

① Torque tube

：NCF600(standard), SUS316L,

NW0276

② Bonnet

：SCPH2, SCS13A, SCS14A,

SCS16A, NW0276

③ Chamber

：Carbon steel, SUS304, SUS316,

SUS316L, NW0276

④ Displacer

：SUS304, SUS316, SUS316L,

NW0276, MONEL, Others

⑤ Transmitter housing ：ADC12

11）Local indication

：LCD display

Line 1 Function indication in 4

digits

Line 2 Data indication in 4 digits

Line 3 Bar graph in percent

12）Output, Power supply, Communication

・Output 4 to 20 mA DC, 2 wire system with HART (version 6)

Supply voltage (UB) and Max. Load (Ra)

UB

：8 to 40 V DC

Max. load (Ra)

：Ra = (UB − 8 V)/0.0248 A (Ω)

4 to 20 mA DC signal ：conforms to NAMUR NE43

Operating range

：3.9 to 20.5 mA DC

Burn-out

：The output is selectable from

"less than 3.5 mA" or "more than

21.6 mA" or "remain stationary

Communication

：

HART

：Version 6 single drop or multi

drop（Ra shall be Ra ≧ 250Ω）

・FOUNDATION Fieldbus

Supply voltage

：9 to 32 V DC ✽1

Base Current

：27 mA DC or less

Input and output signals ：conform to IEC 61158-2

Communication protocol ：FOUNDATION Fieldbus H1

H1 Profile Class

：31PS, 32L

H1 Device class

：Link Master

Function block

：1-RB2, 1-AI, 1-TB

Device type

：0002 (Hex) (FST4000FB)

ITK version

：6.0.1

✽

1 When a safety barrier is used in intrinsically safe circuit,

the supply voltage is 9 to 24 V DC. FISCO explosionproof

9 to 17.5 V DC

13）Accuracy

：±0.5%F.S (Based on mass

conversion correction at factory

calibration)

14）Protection class

：IP66&IP67 (IEC 60529/JIS C0920)

15）Explosionproof classification

① Flameproof

：TIIS Exd IIC T6...T1

ATEX & IECEx Ex db h IIC

T6...T1Ga/Gb ✽2

KOSHA, NEPSI

② Intrinsically safe

：ATEX & IECEx Ex ia IIC

T6...T1Ga ✽2

KOSHA, NEPSI

✽

2 Refer to instruction manual

16）Cable entry

：G1/2, 1/2NPT, M20 x P1.5

The TIIS flameproof with HART

(explosionproof and communica-

tion code: 1) comes with a dedi

cated flameproof packing type

grand cable.

Cable outer diameter: φ6 to 8

(standard)

Spare gasket: φ8 to 10 type,

φ10 to 12 type

17）Painting

: Transmitter Munsell 7.5BG4/1.5

Chamber silver

No painting on stainless steel

components

18）Related standards referred：IECEx, ATEX, TIIS, EMC

19）Functional safety

：SIL2 compatible with IEC61508

20）RoHS Directive

：Complied with

21）Product mass

：Pressure rating class 150

approx. 30 kg

Pressure rating class 600 approx.

35 kg

22）Setting

：Following operation and settings

are available either remotely

through HART or locally by the

magnet key operation. Zero ad-

justment, Span adjustment,

Output simulation test, Damping

adjustment, Setting of burn-out,

Density.

TG-L2610-E00

1st edition Jun 2025 K