For assembling onto devices, test plants and generalindustrial processes

M-900 Series
MICRO FLOWMETEROUTLINE
M-900 series MICRO FLOWMETER is a metal tube
variable area flowmeter for small flow measurement.
All metallic construction covers even high temperatureand high pressure applications.
Thanks to compact design, M-900 is suitable forassembling onto various devices. It also covers small
sized industrial processes.
M-900 series MICRO FLOWMETER has been used fornuclear power plants for long time and HPGSL certified
version is also available.
In addition to local indication, alarm output andpneumatic transmission types are ready to meet yourrequirements of remote monitoring and control.

FEATURES❏ Compact design
Small and light design offers easy installation ontopanels as well as process pipings.
❏ High sensitivity
The pivot bearing and light weight pointer enable tofollow float movement swiftly.
❏ Suitable for corrosive and opaque fluids
Anti-corrosive materials such as titanium and MA276
are available to meet your specifications.

OPERATING PRINCIPLE
The flow path has a tapered part. A float in which amagnet is moulded is located in the tapered tube. The
fluid is introduced from the bottom end of flowmeterand goes through the tube upward.
Because of the differential pressure produced by thefloat and tapered tube, the float is pushed upward
and stops at a position where the weight of float andthe differential pressure balance. Thus, the positionof float corresponds to the flow rate. The moulded
magnet in the float attracts the pointer, and the pointerindicates the flow rate on the scale plate.
The inside of the tube and indication mechanism aretotally isolated by magnetic coupling.
Connection❏ Easy reading of scale and pointerThe long pointer and wide linearized scale plate makeyour reading easier.
❏ Supporting devices
Various supporting devices to meet your requirements
are available such as flow control needle valve, strainer
and constant flow valve.

OUT

Indicator
Scale plate
Pointer

Float(Built in magnet)

Tapered tube
Float rodIN

TG-F2287-E02
3rd edition Nov 2024 K
1st edition Sep 2022 K

M-900 Series MICRO FLOWMETERMODEL CODE
MODEL CODE –M–9Construction

IS –Function

Flow direction–Dust-proof and weatherproof
Intrinsically safe *2Local indication
Pneumatic transmission
Alarm output with reed switch
Bottom to Top
Bottom to Top side
Bottom side to Top side
Bottom side to Top01512
3
4

Bottom rear to Top rear (only available for local indicator type)5
Additional function 1Contents– D– DU

Additional function 2Special

With liquid damper *2
With gas damper– VU Needle valve at outlet– VL Needle valve at inlet/Z*1 Intrinsically safe type is applied only for alarm output type IS-M-95□.
*2 Liquid damper can be provided on the flowmeters with Bottom side→□and Bottom rear→Top rear connections only.

ADITIONAL FUNCTION
1. Liquid damper Model M-9••-DA damper mechanism is required for gas and steam
measurement especially at low pressure service toprevent float hunting.
The damper installed at the bottom of flowmeterensures the accuracy and durability of flowmeter.
The damping mechanism works to reduce theabrupt movement of float utilizing the resistancegenerated between oil in the damper and damping
element connected to float rod.
The damper is recommended also for the liquid
service having a pulsation flow.							2. Gas damper Model M-9••-DU
The gas damper which requires no damper liquid
is available for gas measurement. A mechanicaldamper consists of a cylinder and a pistonconnected with float rod. This type needs no spacefor damping mechanism at the bottom of flowmeter.
Therefore, this damper is applied for any direction
type of flowmeters which result in the flexibility of
piping design. Furthermore unnecessary re-filling of
damper liquid improves the maintenability.
The gas damper is effective for the low pressure gas
services which cause hunting of indication and forthe services which does not permit damping liquids.
It is highly recommended to have gas damper forthe services less than 0.3MPa pressure and without
needle valve at the downstream.
However, this type is applicable only for drygas services and not applicable for liquids nor
condensable vapors. Neither chlorine gas which issynthesized easily with other chemicals nor gases
containing foreign materials like rust, dust and oil

2TOKYO KEISO CO., LTD.

is applicable because of the ingress into the pistonand cylinder which might lead to the malfunctioningof the flowmeter.							3. Needle valve M-9••-V•
A needle valve used for flow rate control isrecommended at the downstream of flowmeter toavoid hunting for gas measurement.
On the other hand, for liquid measurement thepulsation may be eased by the valve locatedupstream.
4. Magnet strainer. See clause "Accessories" at thefollowing page.
The iron particles contained in fluids may cause themalfunctioning of flowmeter due to the attracted
irons on the moulded magnet in the float. The
particles can be eliminated with the magnet strainer
at the inlet of the flowmeter. For this purpose
dedicated strainer with 100 mesh (optionally 200mesh) is available.
5. Purge set. See clause "Accessories" at thefollowing page.
Purge set of M-900 micro flowmeter and constantflow valve keeps constant flow rate even supply
pressure or down stream pressure is fluctuated.

TG-F2287-E02

M-900 Series MICRO FLOWMETERACCESSORIESNEEDLE VALVES
Needle valve for flow adjustment. It will be assembled onto flowmeter● External dimension of M-901-V (With valve)
Standard type(Max.66)● STANDARD SPECIFICATION
Nominal sizeRc3/8

Fluid pressure

Max. 3 MPa

Fluid temperature–15 to +150°C

Material

SUS316/PTFELHigh pressure versions are available on request.

120

140

Consult factory for details

4350.562
112.5

Thread size

Rc1/4

Rc3/8

Rc1/2

L (mm)

245

225275* Screw socket (s) provided for Rc1/4 and Rc 1/2.
* "L" length of the flowmeter with gas damper isextended by 40mm at downstream.

MAGNET STRAINER
A magnet strainer will be assembled into the flowmeter before deliv-● External dimension of MAGNET STRAINER

ery on request.
● STANDARD SPECIFICATION
Nominal size

1/4”, 3/8”, 1/2”

Fluid pressure

Max. 1.5MPa

Fluid temperature

Max. 200°C

Filter Std.

100 mesh		(200 mesh as option)

Material

SUS304, SUS316

PURGE SET
Separate TECHNICAL GUIDANCE of "C" Series is available on re-● CM-21-900 TYPE PURGE SET

quest for this version.

TG-F2287-E02

TOKYO KEISO CO., LTD.

3

M-900 Series MICRO FLOWMETER

Local Indication version
STANDARD VERSIONOUTLINE
Model M-900 is a local indicator for very small flow measurement.
It indicates flow rate of liquids and gases with a scale and a pointer.
Its purely mechanical construction requires neither electric power nor air.

STANDARD SPECIFICATION
Liquids and Gases(The models with a damper are recommended
for low-pressure gases (less than 0.3 MPa) in
the flow range of 60 L/h (nor) or higher.)
Large-flowtype

Standard type

Indication
accuracy *5[%F.S.]

10 to300 to 600
300
60 to150 to 300 to 8,500 to150
300
8,500
17,000Max. 10 (Option: 20)(Subject to flange ratings for the flange
connection)(Max. 2.94 for the types with a liquid damper)
0 to 149
0 to(High- and low-temperature types: −20
120 *3to 200 *4)±5±3±5(High-accuracy(High-accuracytype: ±3)
type: ±2)

Rangeability

10:2

Liquid *1
0.5 to 2[L/h]Gas *1 15 to 60[L/h (nor)]*2

Fluid pressure[MPa]

Connection

Fluid temperature[ºC]

2 to 55 to 10

10:2(Option:10:1)

Paint

Munsell 7.5BG4/1.5 (Indicator housing)

AMB. Temp.

–30 to 80°C

Enclosure of indication partDust-proof and splash-proof

10:1(Equivalent to IP54) (Option: Equivalent to IP65)

Screw

1/4, 3/8 (Standard), 1/2

3/8, 1/2(Standard),
3/4

Flange

10A, 15A, 20A, 25A

15A, 20A,25A*1 Liquid: water (density of 1.0 g/cm3, viscosity of 1.0 mPa·s),
Gas: air (0ºC, 0 MPa)
*2 Models with a damper are not available.
*3 Allowable thermal shock: 80ºC or lower*4 Models with a damper are not available. The fluid temperaturemust be −15 to 150ºC for the models with a needle valve.
*5 Flowmeters for liquids with the specified indication accuracies
may not be available depending on the liquid viscosity.

DIMENSIONS● STANDARD, SCREW CONNECTION M-901

120Flowrange

L

Type

140

Measuring fluid

4350.5

Viscosity limit for liquid flow measurement
Fill scale
up to 2 L/h
2 to 20 L/h
20 to 50 L/h
50 L/h or higher

Viscosity limit (mPa·s)
15
1020

62
112.5

Screw size

1/4

3/8

1/2

L (mm)

180

160190* Screw socket (s) provided for Rc 1/4 and Rc 1/2.
* "L" length of the flowmeter with gas damper is extended by 40mm at downstream.

● STANDARD, FLANGE CONNECTION M-901

Available materialBody

SUS304

SUS316, (SCS14) SUS316L,Equivalent to MA276 *1, Titanium *1

Tapered tube

SUS304 *2

SUS316, SUS316L,Equivalent to MA276 *1, Titanium *1

Float

SUS304

SUS316, SUS316L,
Equivalent to MA276 *1, Titanium *1

120Std.

260

Part name140

Material availabilty*1 Not applied for flowmeter with gas damper type.
*2 Heat-resistant glass, FEP, or PTFE is available for liquids and gases withflow range of less than 2 L/h and 60 L/h (nor), respectively.
(External pressure-resistance is not required for these flow ranges.)
4350.562112.5* Length of flowmeter with gas damper is extended by 40mm at downstream.

4TOKYO KEISO CO., LTD.

TG-F2287-E02

M-900 Series MICRO FLOWMETER● LARGE FLOW VERSION, SCREW CONNECTION M-901

120140120LL140● HIGH/LOW TEMP. VERSION, SCREW CONNECTION M-901

(53)

50.5

(79)

62
112.5

50.5
4362
112.5

Screw size

1/4

3/8

1/2

Screw size

3/8

1/2

3/4

L (mm)

180160190

L (mm)

230265245* The gas damper is not applied for this version. AM type is recommended.

* Screw socket (s) provided for Rc 1/4 and Rc 1/2.
* The gas damper is not applied for high and low temperature version.

● LARGE FLOW VERSION, FLANGE CONNCTION M-901

(53)
(79)

50.5120140330120260140● HIGH/LOW TEMP. VERSION, FLANGE CONNECTION M-901

62112.5
4350.562112.5* The gas damper is not applied for high and low temperature version.

TG-F2287-E02* The gas damper is not applied for this version. AM type is recommended.

TOKYO KEISO CO., LTD.

5

M-900 Series MICRO FLOWMETERFOR GAS SERVICES WITH LIQUID DAMPEROUTLINE

STANDARD SPECIFICATION

M-90□-D equipped with liquid damper is exclusively used for low

Measuring rangepressure gas services.
The other specifications are same as the M-900 series used forgeneral purposes.
(High and low temperature types are not available.)

TypeGases *L/h (nor)Standard type

Min. 0 to 60
Max.0 to 8500

Large flow type

Min. 0 to 8500
Max.0 to 17000*: Air, 0°C, 1atm

Fluid pressure

Max. 3MPa subject to flange rating for flange
connection type.

Flange size 10A 15A 20A 25A

Screw size 1/4 3/8

Standard L 240

240 240 240

typeStandard LA 100

100 100 100typeA40LargeﬂowtypeL

290 290 290

L260 260 270 240A

100 100 100

Large
ﬂowtypeA

40

1/245454545

DIMENSIONS
M-904-D
STANDARD, SCREW CONNECTIONLARGE FLOW, SCREW CONNECTION

4362
112.5

L (3/4)62112.5(150)

(150)

50.5

L (1/4，3/8，1/2)

120140L (1/4，1/2)

120

L (3/8)140(53)50.5

AA

STANDARD, FLANGE CONNECTIONLARGE FLOW, FLANGE CONNECTION

43

62
112.5

120140L

L120140(53)50.562
112.5

A

6TOKYO KEISO CO., LTD.

(150)

(150)

50.5

3/4210 190 215

ATG-F2287-E0255

M-900 Series MICRO FLOWMETER

Pneumatic output version
OUTLINE
M-910 is a metel tube micro flowmeter with pneumatic transmitter.
In addition to local flow indication by scale plate and pointer, pneumaticoutput of 20 to 100kPa is obtained. Air supply and output pressuregauges are provided for checking of operating condition. Air-set (Filterregulator) is optionally integrated.

STANDARD SPECIFICATION
Measuring fluid

Liquids and Gases
The model with damper, M-91□-D or M-91□DU is recommended for low pressure gas
services of less than 0.3MPa.

Measuring range
TypeLiquids *1 L/hGases *2 L/h (nor)Standard type

Min. 0 to 2
Max.0 to 300

Min. 0 to 60
Max.0 to 8500

*1: Water (density 1.0g/cm3, viscosity 1.0 mPa·s)*2: Air at 0°C, 1atm

Fluid temperature

0 to 80°C

Indication Accuracy ±5% F.S.
Enclosure of indication part

DIMENSIONS● STANDARD, SCREW CONNECTION M-911

Dust-proof and splash-proof (Equivalent toIP54)

SPECIFICATION OF PNEUMATIC TRANSMITTER
Output20 to 100kPa against 0 to 100% span
(0.2 to 1.0 barG available on request)

Air supply
Air consumpion

0.14 (±0.01)MPaApprox. 14L/min. (nor)AMB. Temp–30 to 60°CConduit

Rc1/4

Pressure gauge

0 to 0.2MPa range pressure gauges areprovided both for air supply and outlet

Output accuracy
Enclosure±1% F.S. (against flow calibration)
Dust-proof, splash-proof (equivalent to IP54)

The other specifications are same as the M-900 series used forgeneral purposes.
High and low temperature types, and large flow type are not available.

Screw size

1/4

3/8

1/2

L (mm)

180160190* Screw socket (s) provided for Rc 1/4 and Rc 1/2.
* "L" length of the flowmeter with gas damper is extended by 40mm at downstream.

● AIR SET INTEGRATED, FLANGE CONNECTION M-911* Length of flowmeter with gas damper is extended by 40mm at downstream.

TG-F2287-E02

TOKYO KEISO CO., LTD.

7

M-900 Series MICRO FLOWMETER

Alarm output with reed switch
OUTLINE
M-950 is a metal tube micro flowmeter with reed swich alarm contact.
It addition to local flow indication by scale plate and pointer,
alarm contact output at set point is obtained.

STANDARD SPECIFICATION
Measuring fluid

Liquids and Gases
The model with damper, M-95□-D or M-95□DU only applied for standard type is recommended for low pressure gas services of lessthan 0.3MPa.
Large flow type with damper is not available.

Connection diagram

Measuring range
TypeLiquids *1 L/hGases *2 L/h (nor)Standard type

Min. 0 to 2
Max.0 to 300

Min. 0 to 60
Max.0 to 8500

Large flow type

Min. 0 to 300
Max.0 to 600

Min. 0 to 8500
Max.0 to 17000*1: Water (density 1.0g/cm3, viscosity 1.0 mPa·s)*2: Air at 0°C, 1atm

Fluid temperature

0 to 80°C

Enclosure of indication part(Following diagram shows thecase of non alarming status) Terminal
12
3

Reed switch

DIMENSIONS (M-951 TYPE)● STANDARD, SCREW CONNECTION M-951

Dust-proof and weatherproof (Equivalent toL

1 contact by reed switch

45

Type of contact

140

SPECIFICATION OF ALARM CONTACT

120IP54)

Either "a" or "b" instantaneous contact.
Provide holding circuit if required.
Reset span

Less than 30% F.S.

Alarm setting

Adjustable within the measuring range with

G1/2
4350.562

external setting knob
Setting accuracy
Contact capacity±3% F.S. (against flow calibration)

Max. current

0.25 A

Max. voltage

100V DC,125V AC

10VA AC (Resistance load), 10W DC

Insulation resistance 100MΩ or more at 500V DC
Withstand voltage

1500 V AC (1 min.)Cable entry

G1/2

Safety barrier

Type EB3C-R manufactured by IDEC will be35(33)

180.5

Screw size

1/4

3/8

1/2

L (mm)

180160190* Screw socket (s) provided for Rc 1/4 and Rc 1/2.
* "L" length of the flowmeter with gas damper is extended by 40mm at downstream.

● STANDARD, FLANGE CONNECTION M-951

supplied on your request.

120140general purposes.

260

The other specifications are same as the M-900 series used for
45(High and low temperature types are not available.)
G1/2
4350.562180.535(33)* Length of flowmeter with gas damper is extended by 40mm at downstream.

8TOKYO KEISO CO., LTD.

TG-F2287-E02

M-900 Series MICRO FLOWMETER* Specification is subject to change without notice.

Head Office : Shiba Toho Building, 1 – 7 – 24 Shibakoen, Minato-ku, Tokyo 105 – 8558
Tel : +81-3 – 3431 – 1625 (KEY) ; Fax : +81-3 – 3433 – 4922
e-mail : overseas.sales@tokyokeiso.co.jp ; URL : https://www.tokyokeiso.co.jp
TG-F2287-E029