Spirax Sarco M841 flow computer can be used with ILVA pipeline units to measure a variety of fluids, including steam, water, and compressed air. Multiple installation configurations are available, including wall-mounted and panel-mounted versions. M841 provides density compensation for saturated and superheated steam based on input pressure or temperature signals, and displays cumulative flow, instantaneous flow, temperature, pressure, and density.

Features

Suitable for steam, gases, and liquids.

Automatically determines whether steam is superheated or saturated based on temperature and pressure values, then obtains the corresponding density value from the appropriate reference table.

Automatically compensates for density, temperature, Reynolds number, and expansibility coefficient.

Class 0.1 accuracy, high-definition true-color LCD display, low-flow billing, steam-shutoff detection, billing for consumption exceeding the planned amount, power-failure data logging, and paperless recording. Meets metering requirements for trade settlement.

Automatically stores the latest 65536 sets of historical data. The storage interval can be configured, and historical curves for instantaneous flow, fluid temperature, and fluid pressure can be plotted in true color.

Real-time clock and scheduled automatic meter-reading functions.

Password protection prevents unauthorized personnel from changing configured data.

Screen saver function extends screen service life.

Data is retained during power failures. Power-failure data protection does not require a backup battery and provides a protection period of 10 years.

Technical Specifications - Inputs

4 - 20mA (differential pressure/pressure)	Active input (M841 supplies power to the sensor)
Input impedance: 100 ohms	Input power supply (maximum): 100mA
PT100 temperature signal input: range: -200-560℃	± 0.3℃ (when t ≤ 300℃); ± 0.1% (when t >300℃)

Technical Specifications - Power Supply

Power supply:	85-264V, 50Hz±5%
Power consumption	5W

Technical Specifications - Outputs

4 - 20mA	Active output (M841 supplies power externally)
(flow retransmission)	Load impedance (maximum): 600 ohms
	Data update interval: 0.5s
Communications	Communication interface: EIA RS-485 (standard)
	Communication rate: 9600, 4800, 2400, or 1200 baud (selected through the panel)
	No parity, 8 data bits, 1 stop bit
	Transmission medium: twisted pair

Environmental Conditions

Operating temperature: 0 ~ 50℃; relative humidity: 0 ~ 85%

Installation

Panel-mounted instruments are secured to the panel using two supplied mounting brackets. Wall-mounted instruments are secured to a wall or column using three M6 screws.

Notes

When powered by a UPS, installing a 10VA isolation transformer in the power supply circuit is recommended to prevent high-frequency signal interference.

Options and Weight

• Wall-mounted version: supplied with a stainless steel enclosure, weight 8kg, external power supply 220V, internally regulated to 24Vdc.

• Panel-mounted version: installed on a control console or in an existing control cabinet, weight 2kg. Standard power supply can be 220Vac; 24Vdc is available as an option (must be specified when ordering).

Ordering Information

Example: One Spirax Sarco M841 wall-mounted flow computer, 24Vdc.