Description

The Spirax Sarco TVA flowmeter is designed for steam mass flow measurement using the target principle. Flow acting on the internal cone generates a force that is converted into a density compensated mass flowrate. The unit provides loop-powered 4-20 mA output, pulsed output, totalised flow indication, and Modbus communications.

It is intended for saturated steam service as standard. For superheated steam service, the flowmeter is used together with a dedicated pressure sensing kit and high-pressure U syphon assembly.

Sizes and pipe connections

The TVA flowmeter is available in three nominal sizes:

Size
DN50
DN80
DN100

The wafer body is suitable for installation between the following flange standards:

Standard	Rating
EN 1092	PN16, PN25, PN40
BS 10	Table H
ASME B16.5	Class 150, Class 300
JIS	20
KS	20

The flowmeter should be installed in pipework manufactured to BS 1600, ASME B36.10 Schedule 40, or EN 10216-2 / EN 10216-5 equivalent. For other pipe schedules, Spirax Sarco recommends checking suitability before installation.

Pressure and temperature limits

Item	Value
Maximum design pressure	32 bar g @ 239 degC
Maximum design temperature	239 degC
Minimum design temperature	0 degC, non-freezing
Maximum operating pressure, superheated steam, horizontal flow	23 bar g @ 239 degC
Maximum operating pressure, saturated steam	32 bar g @ 239 degC
Maximum operating pressure, vertical flow	7 bar g @ 170 degC, saturated steam only
Minimum operating pressure	0.6 bar g
Maximum operating temperature, saturated steam	239 degC
Minimum operating temperature	0 degC, non-freezing
Maximum electronics ambient temperature	55 degC
Maximum electronics humidity	90% RH, non-condensing
Cold hydraulic test pressure	52 bar g

The product must not be used in the software-limited region shown on the pressure / temperature graph.

Superheated steam accessories

Item	Value
High-pressure U syphon maximum design pressure	80 bar g
High-pressure U syphon maximum design temperature	450 degC
High-pressure U syphon maximum working condition	60 bar g @ 450 degC
Pressure sensing kit maximum operating temperature	125 degC
Pressure sensing kit minimum operating temperature	0 degC, non-freezing
Pressure sensing kit maximum operating pressure	50 bar g
Pressure sensing kit maximum ambient temperature, cable and connector	70 degC

* The pressure sensing kit and high-pressure U syphon are required for superheated steam service.

Materials

Unit	Part	Material
TVA flowmeter	Flowmeter body	Stainless steel S.316 / 1.4408 / CF8M
TVA flowmeter	Internals	431 S29 / S303 / S304 / S316
TVA flowmeter	Spring	Inconel X750 or equivalent
TVA flowmeter	Flowmeter stem	Stainless steel 300 series
TVA flowmeter	Electronics housing	Aluminium LM25
Pressure sensing kit	Cable	Polyvinyl chloride, PVC
Pressure sensing kit	Sensor housing	AISI 304 stainless steel 1.4301
Pressure sensing kit	Sensor	AISI 630 stainless steel 1.4542
Pressure sensing kit	O-ring	Nitrile butadiene rubber, NBR
Pressure sensing kit	Adaptor	AISI 431 stainless steel 1.4057
High-pressure U syphon assembly	Tube	Carbon steel BS 3602 Part 1 1987 CFS 360, zinc plated and passivated
High-pressure U syphon assembly	Valve body	Carbon steel
High-pressure U syphon assembly	Valve seat	PEEK / Polymain

Technical data

Item	Value
IP rating	IP65 with correct cable glands
Power supply	Loop powered
Power supply with optional RS485	24 VDC
Outputs	4-20 mA, not available with RS485 option
Outputs	Pulsed output, Vmax 28 Vdc, Rmin 10 kOhm
Communication	Modbus EIA 232C, RS232C
Communication with optional RS485	EIA 485, RS485C

Dimensions and weights

Dimension X is the recommended minimum distance between the pressure tapping and the flowmeter. It may be increased provided the cable length allows. Standard cable length is 1 m.

Size	A mm	Flowmeter OD mm	C mm	D mm	E mm	F mm	G mm	X mm	TVA kg	Superheat kit kg	U syphon kg
DN50	35	103	322	125	65	250	160	300	2.67	0.3	0.5
DN80	45	138	334	115	65	270	160	300	4.38	0.3	0.5
DN100	60	162	344	155	65	280	160	300	7.28	0.3	0.5

Performance, pressure drop, and sizing

The TVA has integral electronics and an LCD display in the electronics head. The M750 display unit can be used for remote indication via the 4-20 mA output.

System uncertainty, to 95% confidence, 2 STD, in accordance with ISO 17025:

• plus/minus 2% of measured value from 10% to 100% of maximum rated flow
• plus/minus 0.2% FSD from 2% to 10% of maximum rated flow
• Turndown up to 50:1

Pressure drop across the TVA at maximum rated flow:

• DN50: 750 mbar, 300 inches water gauge
• DN80: 498 mbar, 200 inches water gauge
• DN100: 498 mbar, 200 inches water gauge

Flow capacities and pressure drops

Flowmeter type	Maximum Qe litres/min	Minimum Qe litres/min	Maximum DP Wg	Maximum DP mbar
DN50	300	3	300	750
DN80	770	8	200	498
DN100	1200	12	200	498

Sizing for saturated steam, horizontal installation

Size	Duty	1 bar g	3 bar g	5 bar g	7 bar g	10 bar g	12 bar g	15 bar g	20 bar g	25 bar g	30 bar g	32 bar g	Unit
DN50	Max. flow	619	859	1042	1196	1395	1513	1676	1918	2135	2335	2409	kg/h
DN50	Min. flow	12	17	21	24	28	30	33	38	43	47	60	kg/h
DN80	Max. flow	1588	2204	2674	3070	3581	3885	4301	4922	5480	5994	6183	kg/h
DN80	Min. flow	32	44	53	61	72	78	86	98	110	120	128	kg/h
DN100	Max. flow	2475	3435	4167	4784	5581	6054	6703	7671	8540	9341	9637	kg/h
DN100	Min. flow	49	69	83	96	112	121	134	153	171	187	192	kg/h

Notes:

1. Maximum steam flowrates are calculated at maximum differential pressure.
2. The table is a guide for saturated steam service.
3. For superheated steam capacities, Spirax Sarco directs users to its sizing software.

Installation guidance

For full details, refer to the installation and maintenance instructions supplied with the product. Main points:

1. Provide at least 6 pipe diameters of straight pipe upstream and 3 downstream.
2. Where an increase in nominal pipe diameter is required upstream, use 12 diameters of straight pipe upstream.
3. If the TVA is installed downstream of two 90 degree bends in two planes, a pressure reducing valve, or a partly open valve, allow 12 upstream diameters.
4. Pipe internal diameters should be smooth; seamless pipe is preferred and intrusive internal weld beads should be avoided.
5. Install the flowmeter concentrically in the line.
6. Saturated steam service up to 7 bar g may be in any orientation. Superheated steam service must be horizontal, with the electronics below the pipeline.
7. Provide correct line drainage, support associated pipework properly, use eccentric reducers for line size changes, and do not insulate the TVA body or mating flanges.
8. Do not install where the meter will be exposed to driving rain or freezing conditions.

Additional installation points from the essential guide:

• The electronics housing can be rotated for installation clearance and the retaining screw is retightened to 1.3 N m.
• If the electronics housing is mounted more than 45 degrees away from the vertically downward position, PMO is limited to 7 bar g and saturated steam service only.
• A bypass line allows safe removal for maintenance or calibration and enables isolation for re-zeroing.

Spare parts and accessories

Available accessories and service items listed in the product literature include:

• Spare electronics front panel with standard RS232C communications
• Spare electronics front panel with RS485 communications converter
• Pressure sensing kit for superheated steam service
• High-pressure U syphon assembly for superheated steam service

Ordering guidance

Typical ordering descriptions in the literature are:

• Saturated steam service example: 1 off Spirax Sarco DN100 TVA flowmeter for installation between EN 1092 PN40 flanges for saturated steam at 10 bar g, maximum flow 5581 kg/h.
• Superheated steam service example: 1 off Spirax Sarco DN100 TVA flowmeter, pressure sensing kit, and U syphon for installation between EN 1092 PN40 flanges for superheated steam at 10 bar g.