Showing posts with label flow meter. Show all posts
Showing posts with label flow meter. Show all posts

Tuesday, August 8, 2017

Orifice Plate - Primary Flow Element

orifice plate drawing
Orifice plates are simple in appearance, but exhibit
precision machining.
Image courtesy of Fabrotech Industries
An orifice plate, at its simplest, is a plate with a machined hole in it. Carefully control the size and shape of the hole, mount the plate in a fluid flow path, measure the difference in fluid pressure between the two sides of the plate, and you have a simple flow measurement setup. The primary flow element is the differential pressure across the orifice. It is the measurement from which flow rate is inferred. The differential pressure is proportional to the square of the flow rate.

An orifice plate is often mounted in a customized holder or flange union that allows removal and inspection of the plate. A holding device also facilitates replacement of a worn orifice plate or insertion of one with a different size orifice to accommodate a change in the process. While the device appears simple, much care is applied to the design and manufacture of orifice plates. The flow data obtained using an orifice plate and differential pressure depend upon well recognized characteristics of the machined opening, plate thickness, and more. With the pressure drop characteristics of the orifice fixed and known, the measuring precision for differential pressure becomes a determining factor in the accuracy of the flow measurement.

There are standards for the dimensional precision of orifice plates that address:
  • Circularity of the bore
  • Flatness
  • Parallelism of the faces
  • Edge sharpness
  • Surface condition
Orifice plates can be effectively "reshaped" by corrosion or by material deposits that may accumulate from the measured fluid. Any distortion of the plate surface or opening has the potential to induce measurable error. This being the case, flow measurement using an orifice plate is best applied with clean fluids.

Certain aspects of the mounting of the orifice plate may also have an impact on its adherence to the calibrated data for the device. Upstream and downstream pipe sections, concentric location of the orifice in the pipe, and location of the pressure measurement taps must be considered.

Properly done, an orifice plate and differential pressure flow measurement setup provides accurate and stable performance. Share your flow measurement challenges of all types with a specialist, combining your own process knowledge and experience with their product application expertise to develop an effective solution.

Tuesday, September 27, 2016

Multivariable Flow Measurement For Liquids, Gases, and Steam

Insertion flow meter for steam, liquids, or gases
RIM 20 Rotor Insertion Flowmeter
Courtesy Spirax Sarco
Combining multiple measurement capabilities into a single instrument is generally advantageous over installing separate devices to cover an array of parameters. A simple reduction in fittings and connection complexity can bring enough benefit to justify a selection of an instrument with expanded functionality.

Spirax Sarco provides a multivariable rotor insertion flowmeter, available in four configurations to match a broad range of flow measurement needs. All are based on a turbine rotor which is inserted in the fluid flow path. The instrument detects passage of the turbine blades by a sensor, using the measured frequency to determine flow velocity. Further processing with other measurements can provide volumetric and mass flow.

One version of the instrument delivers only volumetric flow rate. A second variant adds a temperature sensor and is capable of providing a temperature compensated mass flow reading. This model is often applied for measuring saturated steam.

A fuller featured version incorporates a pressure sensor along with the temperature sensor and can function as a flow computer, providing instantaneous readings of mass flow rate for gases, liquids, or steam. Several output signals can be configured to provide a selection of mass flow rate, volumetric flow rate, pressure, temperature, or density.

There is also a product version specifically intended for energy monitoring in applications involving steam, chilled water, or hot water. This multivariable version provides energy usage readings in selectable units, as well as supply and return temperatures, delta T, mass total and energy total.

The unique insertion design measures liquids, or gases, including steam, and can be installed without line shutdown. The unit is suitable for applications on line sizes from 2" to 80". More detail is found on the data sheet included below. Contact an instrumentation specialist and share your flow measurement requirements and challenges. The combination of your process knowledge and their product application expertise will produce effective solutions.

Friday, April 29, 2016

Simple BTU Metering For Commercial and Industrial Applications

Illustration of simple BTU metering system showing components
Simple BTU metering setup for closed loop heating or
cooling system
Monitoring thermal energy usage at logical or localized points of consumption can provide a manager some insight into the real costs of process or space operation, as well as where the greatest benefits may be reaped from efforts at maximizing energy efficiency.

Heating and cooling systems or loops that employ water as the heat transfer medium can be simply and economically metered to determine the thermal energy usage of a space or process. The simple setup consists of a flow meter, two temperature sensors, and a calculating module that collects the output from all three devices and produces a summation of the total heat transferred through the system portion served by the subject piping. This arrangement is commonly called BTU Metering.

The size of the system being metered may be an important factor in determining the most effective metering equipment specification. A larger capacity fluid system is likely to benefit from highly accurate measurement equipment, since inaccuracy in temperature or flow measurement is leveraged by the large amount of liquid moving through the system. Heating or cooling systems of small or moderate size tend to be well suited for the application of moderate to good accuracy metering equipment, with its substantially reduced cost of installation and ownership. The key to success is selecting equipment that is well applied for the whole range of anticipated flow rates and temperatures.

If your building, plant, or process currently does not have any thermal metering, the installation of this simple device can provide information that assists in making significant progress in building an energy saving plan. More information is available from product application specialists, as well as consultation on how to most economically accomplish your process energy metering goals. Share your process measurement and control challenges with a product specialist and work together to develop effective and sensible solutions.

Monday, August 10, 2015

Chemical Flow Meters for Hazardous Environments

ISTEC Aquametro Chemical Flow Meter
Chemical Flow Meters for Industrial Process Measurement
Courtesy ISTEC
ISTEC Corporation’s Aquametro Domino line of Chemical Flow Meters provide accurate measurement of water and liquid chemical flows using rotary piston or vane wheel technology. Versions of the instruments are designed for use in safe and hazardous areas (ATEX). The Domino line has flexible mounting configurations to minimize installation space, and is suitable for conductive or non-conductive liquids. Proper operation and accuracy of the instrument is not diminished by flow disturbances. The rugged units are manufactured in a wide array of sizes and configurations to accommodate every application.

Review the product literature below, or contact a product specialist to discuss your water or liquid chemical flow measurement requirement.