Flow Nozzles & Venturis

CPA Sonic Nozzles protect gas meters and other pipe equipment from damaging high velocity flows. They provide reliable and repeatable flow-limiting behavior, and can be manufactured to protect all types of positive displacement, turbine, and orifice meters.

CPA sonic nozzles are manufactured to the ASME 7M industry standard.

Nozzle Features

• Suitable for protection of all types of flow meters, probes, strainers, valves, and other equipment.
• Custom manufactured for your exact process conditions.
• No moving parts, no maintenance requirements, and low fouling rate.
• Available in a range of sizes, and materials.
• Excellent reliability and repeatability.
• Nozzles are manufactured to recognized industry standards, such as ASME/ANSI, or with a stepped throat which increases stability at critical conditions

Operating Principle

Sonic nozzles work by creating a restriction in the pipeline. This restriction forces the gas velocity to increase at the throat of the nozzle. If the pipe flow rate gets high enough, the velocity at the nozzle throat reaches the local speed of sound. When this occurs, the flow is choked, and the mass flow rate through the nozzle cannot increase any further.

A choked nozzle prevents the gas velocity in the pipe upstream of the nozzle from increasing as well. This condition protects anything installed in front of the nozzle, even if the downstream suction pressure continues to be reduced.

The CPA Sonic Nozzle must therefore be installed downstream of the pipe equipment it is meant to protect. The flow velocity in the pipe in front of the nozzle is limited, but high velocity flows are possible downstream of the nozzle.

Sonic Nozzles vs. Orifice Plates

Sonic nozzles offer superior performance and stability compared to restriction orifice plates, while also providing superior pressure recovery at subsonic conditions.

It has been found through testing that an orifice plate does not properly choke, which means the mass flow rate through an orifice plate continues to increase when the downstream suction pressure is reduced. A sonic nozzle, however, will maintain a fixed mass flow rate once choking conditions occur, even if the downstream suction pressure is reduced further. This is why sonic nozzles provides better protection than a restriction orifice plates and also has a lower pressure drop in normal operation.

Sonic nozzles may also be ordered with pressure taps, allowing the nozzles to perform backup or secondary gas measurement service. They can act as both a backup measurement device in the subsonic regime, and as an overspeed protection device when choked.

Installation Information

Sonic Nozzle Installation

The CPA Sonic Nozzle must be installed downstream of the pipe equipment it is meant to protect. While the flow velocity in the pipe in front of the nozzle is limited, high velocity flows are possible downstream of the nozzle.

CPA Sonic Nozzles are typically installed between two raised face flanges, with a gasket on either side of the raised face disk. A portion of the nozzle will be inserted into the pipe. The location of the raised face disk determines whether the nozzle inserts into the pipe upstream or downstream of the nozzle.

A nozzle with the flange on the inlet side is designated “FOUE” and will insert into the downstream pipe. When the flange is on the outlet side, the nozzle is designated “FODE” and will insert into the upstream pipe.

The flange thickness, and the length of insertion is customizable to your needs.

If you need help selecting a product or want further information about customization and manufacturing, please call us directly at 403-236-4480 or 1-888-FIX-FLOW.

The CPA Flow Nozzle is the simplest dP measurement nozzle design offered by Canada Pipeline Accessories. The completed part consists of only the converging inlet contour and the cylindrical throat. Several variations of the CPA Flow Nozzle are available, including the long radius, ISA 1932, and cylindrical inlet nozzle.

The pressure measurements are taken from taps located on the meter run piping, a specific distance from the nozzle. CPA provides guidelines on where to install the meter run pipe taps and what size they must be. However, the meter run piping and the taps themselves are not included with the CPA Flow Nozzle, and must be supplied separately.

All CPA Flow Nozzles are custom designed to your specific conditions, whether liquid, gas, or steam. The beta ratio can by specified directly, or CPA can calculate a beta ratio for you using an approved standard such as ISO 5167, ASME 3M, and ASME PTC-6.

For a customized beta ratio calculation, CPA requires detailed process information including fluid density, flow rate, and desired differential pressure.

Like all CPA products, the CPA Flow Nozzle is available in a wide range of materials and can be customized to suit your specific needs. The CPA Flow Nozzle is designed to be installed between two raised face, full face, or RTJ flanges. It can also be welded between two pipe spools. A portion of the nozzle will extend into the section of pipe located immediately downstream of the flange or weld point.

The CPA Flow Nozzle is intended for subsonic flows only and should not be used in critical choked flow conditions. For flow measurement in sonic conditions, CPA recommends use of a sonic nozzle.

Features

• Very simple design, no moving parts, no maintenance requirements, and low fouling rate.
• Utilizes flange pressure taps or pressure taps installed directly onto the pipe.
• Available for installation between raised face flanges, or for welded applications.
• Custom manufactured for your exact process conditions.
• Available calibration services through one of our test lab partners.
• Available in a large range of sizes, and materials.
• Manufactured to recognized industry standards such as ASME/ANSI/ISO.

We’d be happy to talk with you about your specific needs. Call us at 403-236-4480 or 1-888-FIX-FLOW.

Venturi Tube

The CPA Venturi Tube is a differential pressure measurement device consisting of a cylindrical upstream inlet section, a converging inlet cone, a cylindrical throat, and an expanding outlet cone. The upstream and downstream pressure taps are included in the Venturi Tube design.

The beta ratio can be set to the value you specify, or it can be sized according to your process conditions, using an approved measurement standard such as ASME 3M, ISO 5167, or ASME PTC-6.

All CPA Venturi Tubes are custom designed for your specific application, and all aspects of the Venturi Tube design are customizable, including the overall length, process connections, number of pressure taps, beta ratio, and more. For manufacturing simplicity, CPA typically machines the Venturis out of a single piece of material. Like all CPA products, the Venturi Tube can be manufactured from many different materials are required per the application.

The Venturi Tube is suitable for all liquid, gas, and steam applications.

Venturi Tube Features

• Available calibration services through one of our test lab partners.
• Integrated diffuser reduces the permanent pressure drop compared to flow nozzles.
• Provided with both sets of pressure connections; static and throat pressures. Connections are customizable to your exact requirements.
• Custom manufactured for your exact process conditions.
• Available with bolted flange connections or welded installations.
• No moving parts, no maintenance requirements, and low fouling rate.
• Manufactured to recognized industry standards such as ASME/ANSI/ISO.

Venturi Nozzle

The CPA Venturi Nozzle is a differential pressure measurement device consisting of a converging inlet, a cylindrical throat, and an expanding diffuser cone outlet. It is very similar to a CPA Flow Nozzle, but with a diffuser cone added to reduce the permanent pressure drop of the nozzle.

For downstream pressure readings, the Venturi Nozzle includes a tap at the throat that connects to the nozzle body via NPT or socket weld. For the upstream pressure reading, the tap will be located in the pipe. Optionally, a short cylindrical inlet section with upstream pressure taps can be added to the nozzle design.

The CPA Venturi Nozzle is custom designed according to your specific process conditions, whether the fluid is a gas, liquid, or steam. The beta ratio will be set according to your specifications, or it can be calculated using an approved measurement standard such as ASME 3M, ISO 5167, or ASME PTC-6.

The CPA Venturi Nozzle can be installed between two raised face, full face, or RTJ flanges. It can also be welded between two pipe spools. The number of taps can be varied according to your needs, and the connection to the flange can be designed according to the size of NPT or socket weld you wish to use.

The CPA Venturi Nozzle is intended for subsonic flows only and should not be used in critical choked flow conditions. For flow measurement in sonic conditions, CPA recommends use of a sonic nozzle.

Venturi Nozzle Features

• Available with bolted flange connections or welded installations.
• Integrated diffuser reduces the permanent pressure drop compared to flow nozzles.
• Provided with pressure taps located at the throat. Pressure connections are customizable to your exact requirements.
• Custom manufactured for your exact process conditions.
• Available calibration services through one of our test lab partners.
• No moving parts, no maintenance requirements, and low fouling rate.
• Available in a large range of sizes, and materials.
• Manufactured to recognized industry standards such as ASME/ANSI/ISO.

We’d be happy to give you more information about our Venturi Tubes and Venturi Nozzles. Call us at 403-236-4480 or 1-888-FIX-FLOW.

CPA Sonic Nozzles can be used as a range extender for pressure control valves and volumetric flow meters. The sonic nozzle introduces a pressure drop downstream, which increases the pressure in the meter tube. This allows the flow meter operating range to be extended by moving a larger standard volume of fluid. Because of this, the meter station capital costs can be decreased by downsizing the flow meter and pipe sizes, without compromising flow limits.

Smaller meters with higher velocities, using pipe reducers as a pre-flow conditioning element, give more accuracy by increasing flow conditioner effectiveness.

For a control valve, the nozzle again introduces a pressure drop downstream of the control valve. This reduces the load on the valve and gives it a greater range of control. This has the added effect of reducing the noise the control valve generates.

Range Extender Benefits

• The density of the flow in the meter tube is increased, allowing the flow meter to move a larger standard volume of fluid and extend its operating range.
• Reduce the meter station capital cost by downsizing the flow meters and pipe sizes without compromising flow limits.
• Smaller meters with higher velocities allow for lower uncertainty by increasing flow conditioner effectiveness and using a pipe reducer as a pre-flow conditioning element.
• For redundant measurement, differential pressure can be taken across the flow conditioner, flow meter, flow nozzle, and a combination of these elements or the entire meter tube.
• Reduce or eliminate control valve noise by moving a problematic pressure drop location away from a control valve, and allowing the sonic nozzle to take the pressure drop.

Want more information about range extenders? Give us a call. 403-236-4480 or 1-888-FIX-FLOW.