Download TH-1700/1800-CNG

CNG-FLOWMETER TH-1700/1800-CNG
■ OVERVIEW
Models TH-1700/1800 flowmeters are developed for precise CNG
fuel flow measurement purpose based on widely field proven thermal flowmeter technologies.
■ FEATURES
❏ Measuring Mass Flow
Models TH-1700/1800 flowmeter measurement (shown in standard conditions) is not affected by any change of the pressure of
the gas based on its measuring principle. large gas temperature
fluctuation may only affect negligibly small deviation of its output
that can be compensated by adding temperature measuring
sensor.
❏ High Accuracy ＊
Model TH-1700 and 1800 flow meters provide accuracy of ± 1%
of reading value for flow range from 5% through 100% F.S.
❏ Minute Flow Measurement
Accuracy of ± 1% of reading value is achievable for minute flow,
minimal flow to 0.2Nl/min. ＊
❏ Wide Rangeability ＊
Line-up of meters of five (5) nominal sizes, 15mm, 20mm, 25mm,
40mm and 50mm, cover flow ranges from 0.2 Nl/min. through
4050 Nl/min.
❏ Low Pressure Drop ＊
■ MEASUREMENT PRINCIPLE
Calorific value H lost in unit time from a electrically heated metallic
capillary placed in gas is a function of the Velocity of the gas (U) and
Temperature difference (Δ T) between the gas and the capillary;
that is,
H = f (U・Δ T）
The Joule Heat Value generated from the capillary is function of
voltage and current applied to the metallic capillary; that is,
W = ｆ （V・I)
Pressure drop generated by model TH-1700-CNG is equivalent to
These two values are equivalent during the capillary and gas are in
that of straight pipe. For model TH-1800-CNG that is provided
thermodynamically balanced condition; then, the velocity of the gas
with integrated flow straightener, pressure drop may reach
(U) is obtained as a function of Voltage (V) and Current (I) applied to
850mmH2O at maximum
the capillary; that is,
❏ Easy to Follow Variety of CNG Composition
CNG composition change can easily be programmed into the
convertor for five (5) components, each with 1Vol.% division.
❏ Availability of Measurement of Low Pressure Gas
Measurement is available for gas pressure from 0 to 10 kgf/cm2G
❏ Durable Construction
U = f （V・I)
Flow rate Q of the gas can be obtained from U and A (sectional area
of the conduit); that is,
Q = U・A
Meters are not subjected to deterioration due to wearing, etc.,
since there is no moving part inside of the meters. No periodical
maintenance nor calibration may be required for its simple me-
Temperature Difference : ΔT
Heating Current : （PWM）
I
chanical construction..
❏ Multi-functional Convertor
Chromel
Alumel
The convertor is available to output and indicate Flow Rate, Inte
grated Flow, Integrated Flow for a gated time duration, time duration for a gated flow rate and Alarms, etc. A variety of output
signals provides easy data communication to management com
puters. A variety of setting capability provides measurements to
satisfy the test requirements.
Flow velocity
＊ Refer to table on page 4 for detail.
Capillary - Non-heated
Thermocouple
Capillary - Heated
TG-F1059-0E
JUN. 2011K
MINI-THERMAL CNG-FLOWMETER
■ CONFIGURATION EXAMPLE FOR CNG FUEL FLOW MEASURING SYSTEM
❏ The figure shows a configuration example to measure the flow rate from 1Nl/min. through 400Nl/min. within the accuracy of ± 1%reading.
First 15A detector measures 1 ∼ 2 0Nl/min. flow, and the second detector 20A measures 20 ∼ 400Nl/min. For measurement of flowrate
below the minimum flowrate of each detector, the accuracy of ± 1%reading may not be achieved. Detail shall be referred to the table in
page 4.
Two detectors, both 15A and 20A, shall be connected in series to accomplish continuous measurement for the range from 1Nl/min. through
400Nl/min. In this arrangement, the flow is measured by two detectors simultaneously. The pressure drop will become total of Δ Ps of two
detectors.
❏ In the Figure, model TH-1800-CNG is applied to shorten the total length to obtain high accuracy against the turbulent flow. Model TH-1700CNG, that with low pressure loss, may be recommended for the measuring cases such as production lines of the City Gas, where the pressure is low and the straight length of the piping is insured.
❏ An oil remover should be installed at upstream for services includes oil mist or dust, etc.
❏ Where the engine side is subjected to pulsation flow generated by the injector, a surge tank should be recommended to install.
■ SELECTION OF THE TYPE OF INSTRUMENTS
❏ The model TH-1700-CNG has no obstacle inside except two (2) thin（= φ 0.45）metallic tubes ; therefore, pressure drop generated by them
is almost negligible. Straight piping, 20D for upstream and 5D for downstream, is required for stable and highly accurate measurement.
❏ The model TH-1800-CNG is provided with a built-in flow-conditioner; therefore, a small Δ P may be generated. The model however does not
require any straight run piping; then, it suites for the installation in limited locations or for the measurement of turbulent flow.
■ GENERAL SPECIFICATION
Detail of specifications shall be referred to TECHNICAL GUIDANCE [TH-1700/1800 Series Thermal Flowmeter] and [TRX-700 Thermal Flowmeter Convertor]
Detector（TH-1700/1800-CNG)
Convertor（TRX-700-CNG)
Measuring Gas
: CNG without dust nor mist
Convertor for CNG Flowmeter (Based on standard version TRX-700)
Nominal Diamete
: 15, 20, 25, 40, 50mm
Connection to the Detector : Special Cable for Detector
Connection
: TH-1700-CNG JIS10KRF Flange
with Special Connector to Detector
TH-1800-CNG JIS10KRF Flange or Rc
Screw
Measuring Range
connection
Cable Length
: Refer to table on page 4
Measuring Accuracy : Refer to table on page 4
: 10m (Max 100m)
Indication function
: Refer to right page
Power supply
: AC100V 50/60Hz
Gas Temperature
: 0 ∼ 120℃
Maximum Pressure
: 1MPa
Power Consumption : 50VA approx.
Response Time
: 3sec. (63% Step Response)
Case
: Outer dimensions
Material
: Sensor SUS316 (316SS eq.)
SUS304 or 316 (304SS or 316SS
Signal Output
: DC 4 ∼ 20 ｍ A, Pulse
Fluoro Rubber
Various Data Setting
Body
DC12V or 24V (Option)
W382 x H155 x D350
eq.)
Seal
Construction
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RS485, Flow Alarm Output
: Water-tight (IP65 or equivalent)
TOKYO KEISO CO., LTD.
TG-F1059-0E
MINI-THERMAL CNG-FLOWMETER
RS485
（１）[Flowrate + Temperature]
or
（２）[Integrated Flow (continuous)]
Convertor
1 Flowrate or Temperature
indication
2 Setting Key
3 Flow indication
and Setting Key:
4 Time indication
and Setting Key:
Gate setting for total
flow integration
↓
Indication of Integration Duration
or
Indication of
total flow
integration
↑
Gate setting for
Indication
Duration
TRX-700-CNG
Flow signal Convertor
RS485
Daisychain
Special Cable
TRX-700-CNG
Flow signal Convertor
TH-1800-CNG
15A
Flow Detector
Switching
Valve
Surge Tank
Switching Valve
Oil Remover
TH-1800-CNG
20A
Flow Detector
Gas
Engine
Temperature Detector
Approx. 0.6m
TG-F1059-0E
TOKYO KEISO CO., LTD.
3
MINI-THERMAL CNG-FLOWMETER
■ MEASURING RANGE, ACCURACY AND PRESSURE DROP
The table below shows data for type TH-1800-CNG with built-in flow Conditioner
For TH-1700-CNG, the flow range may slightly differ
❏ Full scale (FS) can be set within the range（← −− →）for each of sizes when placing order.
Example: For 15A meter, the flow range can be set at any ramge between 4Nl/min. through 370Nl/min
❏ Accuracy is ±１ % of reading value for flow of 5% FS and over.
For flow of 5% of FS or below, accuracy is ±[（F.S.x ５ % ｘ１ %)÷ reading] x 100%
For flow below 5% of minimum selectable setting range, the accuracy can not be assured due to unstable flow because of the very slow
flowrate below 2cm/sec.
Example: For 15A meter, if the flow range is set at 370Nl/min, error at 4Nl/min. flow is within ±{(370x0.05x0.01)÷４}ｘ 100 ＝± 4.652％
❏ Pressure drop is shown for Maximum Flow Scale at atmospheric pressure as (mm H2O)
For VNl/min., compensate flow by multiply [V ÷ MaxF.S.]2 to the value above.
] to the value above.
For gas pressure at Pkgf/cm2G, multiply [1.033 ÷（1.033 ＋ P）
Diameter
(Nominal)
CNG Flow
* 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 : [email protected] ; URL : http://www.tokyokeiso.co.jp
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TG-F1059-0E