Steam flow meters help with system performance evaluation in a variety of applications. There are many different types of steam flow meters with each one offering different benefits depending on the application. At Machine Applications Corporation, you’ll find a selection of reliable steam flow meters and transmitters to best suit your needs.


MAC Instruments’ Steam Flow Meters 

Steam To Atmosphere, Open Tank Applications

Repeatable Results, Saves Energy, Speeds Equipment Start-Up

  • Rugged and Reliable
  • Simple to Use
  • Stainless Steel Construction
  • Affordable
  • Easy to Install
  • True Mass Flow Even With Changing Line Pressure



  • Rated Pressure
    • 150 PSIG Max.
  • Ambient Temperature
    • 32° F to 180° F
  • Absolute Pressure Ratio
    • 90% Max.
  • Accuracy
    • ±5 F.S.

Ordering Information

Steam flow meters are described by indicating the following combination of product features.

(Product Code)-(Steam Capacity LB/HR)-(Pipe Size)-(End Connections)-(Flow Direction)

Product code is STM. End Connections, F for Flange (raised face). Flow Direction selections are VD (vertical down), VU (vertical up), HR (horizontal right), or HL (horizontal left).

Example: STM – 1000 – 1.5 – F – HR is a steam flow meter with calibrated scale to 1000 LB/HR, end connections are 1 1/2″ Flange, with a horizontal flow direction, downstream to the right.

Standard Meters
(Full Flow at 75 PSI) (Full Flow at 85 PSI)
STM-250-1 -F-XX STM-125KG-1 -F-XX
STM-500-1 -F-XX STM-250KG-1 -F-XX
STM-250KG-1 -F-XX STM-500KG-1.5 -F-XX
STM-1500-1.5 -F-XX STM-750KG-1.5 -F-XX
STM-2500-2 -F-XX STM-1250KG-2 -F-XX
STM-3000-2.5 -F-XX STM-1500KG-2.5 -F-XX
STM-5000-3 -F-XX STM-2500KG-3 -F-XX

Consult the factory for special configurations.

PDFView the Steam Flow Meter data sheet in pdf form.

FindSteam Flow Meter & Transmitter Applications


Overview of Steam Flow Meters

Steam flow meters provide accurate measurement and steam process control for several end-of-run applications, including atmospheric blanchers, steam injection to process ovens, steam eductors, and other applications involving the exhaustion of steam through nozzles or pipe manifolds to near-atmospheric pressure. These meters provide useful data to assess the performance and efficiency of boilers, and they track the amount of steam a system requires.

Pounds per hour is the measurement unit that indicates the steam’s mass flow rate, with the measurement visible on a calibrated panel gauge that’s easy to understand. The meter is rugged and simple in its design and is installed in series with the steam piping. The mechanical design also eliminates the need to repair or replace any internal moving parts, and the steam flow path avoids obstructions.

The internal components of the steam flow meter feature a 300 series stainless steel construction, which provides added corrosion resistance and durability. The product’s metering components can withstand heavy industrial use, including repeated chemical washdown, continuous operation, and outdoor applications.

Principle of Operation

Operating on critical flow principles, the meter design incorporates a proprietary venturi flow nozzle characterized by a convergent bellmouth inlet, minimum area throat, and conical diffuser.

Upstream pressure is converted to velocity as steam flows through the converging inlet. The velocity increases along the restrictive inlet until sonic velocity is achieved at the nozzle throat. The sonic velocity, or speed of sound, is the maximum obtainable speed at which the flow may pass through the nozzle throat. The sonic velocity is converted back to static pressure in the diffuser.

Mass flow rate is strictly proportional to the upstream pressure. Changes in the downstream pressure do not affect upstream conditions. A downstream change in pressure can not be transmitted through the sonic flow conditions existing at the throat

For the system to operate correctly, a small pressure drop across the nozzle is required. The proprietary inlet, throat, and diffuser designs are such that the exit pressure may be as high as 90% of the inlet pressure for acceptable operation. Steam-to-atmosphere and open tank applications easily meet these operating conditions.


The steam flow meter is an in-line device that will operate in any flow orientation. If desired, the meter may be reconfigured in the field to a different flow direction.

The steam flow rate is controlled by throttling on the inlet side of the steam flow meter. Manual and specialty control valves or pressure regulators may be used as pressure-reducing devices.

When required, non-standard capacities, special construction, or other optional features can be provided.

Find a Distributor

Steam Flow Meter Types

There are several types of steam flow meters, including:

  • Orifice plate flow meters: These flow meters use an orifice plate that features a measuring and drain orifice to measure pressure differentials when steam is flowing.
  • Turbine flow meters: These contain a multi-bladed rotor that rotates in proportion to the velocity of the steam flow, with a magnetic sensor that measures rotational frequency.
  • Variable area flow meters: Also known as rotameters, these feature a tapered and vertical bore tube with a small bore at the low end, along with a float that can freely move. 
  • Spring-loaded variable area flow meters: The balancing force in these meters is a spring, making them independent of gravity, which enables use on any plane.
  • Direct in-line variable area (TVA) flow meters — A precision-shaped moving cone changes the area of an annular orifice that moves against a spring’s resistance.
  • Ultrasonic flow meters: These meters measure the amount of time required for ultrasound pulses to travel between two transducers, which are connected to a monitored pipe.
  • Vortex shedding flow meters: In these meters, vortices are shed from the back of a non-streamlined body that’s placed in the steam flow, allowing for the measuring of velocity.

Common Applications

Many applications and industries use steam flow meters. Some common industries include:

  • Breweries and distilleries
  • Paper
  • Textile
  • Pharma
  • Power
  • Food processing
  • Steel
  • Chemical

Some specific applications include:

  • Injection processes
  • Steam eductors
  • Sparging tanks
  • Humidification
  • Atmospheric blanchers

Contact Our Experts for Your Steam Flow Meter Needs!

Steam flow meters offer a solution for performance assessment across a wide range of applications. At MAC Instruments, we carry a series of reliable steam flow meters as a leading manufacturer of industrial moisture measurement devices. In addition, you can find top-quality industrial moisture analyzers and transmitters for high-temperature applications. At MAC Instruments, we leverage our proprietary sensor technology to provide accurate moisture measurement and analysis without the use of chemicals.

If you would like additional information about our products, contact us and request a quote to find the right solution for your application.