What is an External Spring, Lever & Weight Single Disc Check Valve

Single disk check valve animation.

According to Wikipedia, "Check valves are used in many fluid systems such as those in chemical and power plants, and in many other industrial processes."

Check valve symbol

As shown in the animation to the left, the single disc (swing) check valve use the directional flow to push open a swinging disk. As long as flow continues, the disk stays raised. But as flow stops, gravity allows the disk to re-seat itself and any reverse flow is prevented by the closed disk. As reverse flow pressure increases, the swing check valves seating increases as well.

Single disc check valves also use springs, levers and/or weights mounted on the valve to allow for better control of surge and to prevent the valve from slamming closed. These assemblies are used to vary the valve’s closing operation in order to reduce the severity of the closing water hammer.

External spring, external spring & lever, and external spring, level & weight designs (left to right).
Courtesy of Champion Valve.

For more information on any industrial check valve, contact Piping Specialties, Inc. by visiting https://psi-team.com or calling 800-223-1468.

An Introduction to Triple Offset Butterfly Valves

Triple Offset Butterfly Valve
(Pratt Industrial)

Triple offset butterfly valves are designed to fill the demand for an alternate solution to gate valves and ball valves. They are preferred when weight, space, performance, and the ability to modulate to the process flow are an issue. Typically available in sizes 3" through 48", and in 150, 300 and 600 pressure classes, they're rated for operation from -50 deg. F. through 750 deg. F.

Designed with metal-to metal seats, triple offset butterfly valves provide distinct advantages over traditional gate valves, namely lower weight, zero-leakage, ease in automation, and capable of being used for modulating service.

Industries Using 

• Chemical
• Refinery
• Power
• Steam Generation
• Petrochemical
• Water/Waste Water Treatment

Click on image for larger view.

Triple Eccentric Disc-Shaft Design (diagram above)

• Offset 1: It is accomplished by moving the centerline of the shaft away from the seating plane.
• Offset 2: It is accomplished by moving the centerline of the shaft offset from the centerline bore of the valve.
• These two design features cause the disc to open and close relative to the body seat in a “camming” action and effectuate the position seated valve design which is typical of the High Performance Butterfly Valve, however there is still contact between the disc and the seat in the first several degrees of opening and closing which can cause premature wear of the seat in the general areas.
• In order to achieve an API 598 Shut Off classification a 3rd offset needed to be introduced to make the valve a “torque seated” design with graphite and metal seating surfaces.
• Offset 3: It is accomplished by adjusting the cone angle created by the 1st and 2nd offset angles at some point downstream of the valve in the center of the piping to the adjacent piping wall as depicted in the illustration below “Sticking tendency”. By incorporating the 3 offsets into one design typical of gate valves is eliminated with seat contact throughout the entire stroke reducing run torques and improving actuator modulating performance at the same time.

For more information, contact Piping Specialties by visiting https://psi-team.com or by calling 800-223-1468.

What is a Piping and Instrumentation Diagram (P&ID)?

Piping and  instrumentation diagrams (P&ID's) are schematic representations of a process control system and used to illustrate the piping system, process flow, installed equipment, and process instrumentation and functional relationships therein. They are also known as "process and control flow diagrams".

They are intended to provide a “picture” of all the process piping, including the physical branches, valves, equipment, instrumentation and interlocks. By using a standard set of internationally recognized symbols, each component of the process system - instruments, piping, motors, pumps - is recognized on paper or computer screen.

P&ID’s may be very detailed and are generally the primary source from where instrument and equipment lists are generated. They are also used as a handy reference for maintenance planning and system upgrades. Furthermore, P&ID’s also play an important early role in plant safety planning by providing a thorough understanding of the operability and relationships of all components in the system.

Watch the short video below for more information.

For more information contact:
Piping Specialties / PSI
https://psi-team.com
800-223-1468

Continuous and Point Level Control Selection Guide

Drexelbrook Continuous and Point Level Control Products

Based on experience from of thousands of inquiries about level measurement, most questions boil down to "What is the best level measurement instrument for my application? That depends on quite a few application considerations, such as:

• Will the measured media add coating to the probe?
• Can the probe have contact with the media?
• Are there explosion hazards?
• What is the physical type of application, well, tank, open channel or floating roof tank?

This document can help deliver the perfect continuous level transmitter or level switches for your application.

Download a PDF version of the Drexelbrook Continuous and Point Level Control Selection Guide here, or view the embedded document below.

https://psi-team.com
800-223-1468

Drexelbrook Continuous & Point Level Selection Guide from Piping Specialties, Inc and PSI Controls

Considerations for Choosing Industrial Butterfly Valves

High Performance Butterfly Valve
(Pratt)

Industrial process control valves are available in uncountable combinations of materials, types, and configurations. An initial step of the selection procedure for a valve application should be choosing the valve type, thus narrowing the selection field to a more manageable level. Valve "types" can generally be classified by the closing mechanism of the valve.

A butterfly valve has a disc that is positioned in the fluid flow path. In the most common form of butterfly valve, the disc rotates around a central axis, the stem, through a 90 degree arc from a position parallel to the flow direction (open) to perpendicular (closed). A variety of materials are used in the valve body construction, and it is common to line the valve with another material to provide special properties accommodating particular process media.

What attributes might make a butterfly valve a beneficial selection over another valve type?

Resilient Seated Butterfly Valve
(Pratt)

• The closure arrangement allows for a comparatively small size and weight. This can reduce the cost, space, and support requirements for the valve assembly.
• Generally low torque requirements for valve operation allow for manual operation, or automation with an array of electric, pneumatic, or hydraulic actuators.
• Low pressure drop associated with the closure mechanism. The disc in the flow path is generally thin. In the fully open position, the disc presents its narrow edge to the direction of flow.
• Quarter turn operation allows for fast valve operation.
• Some throttling capability is provided at partially open positions.
• Small parts count, low maintenance requirements.

What may be some reasons to consider alternate valve types?

• Butterfly valve throttling capability is generally limited to low pressure drop applications.
• Cavitation can be a concern.
• Some sources mention the possibility of choked flow as a concern under certain conditions.

Butterfly valves, like other valve types, have applications where they outperform. Careful consideration and consultation with a valve expert is a first step toward making a good selection. Combine your process know-how with the product application expertise of a professional sales engineer to produce the best solutions to your process control challenges.

For more information regarding an type of industrial valve, contact Piping Specialties, Inc. by visiting https://psi-team or by calling 800-223-1468.

MOGAS Severe Service Ball Valve "Mate Lap" Seal Demonstration

The video below demonstrates the effectiveness of the MOGAS "Mate Lap" seal provided on MOGAS severe service ball valves.

MOGAS valves have outperformed others worldwide in some of the most severe service conditions, including: Extreme temperatures; High pressures; Abrasive particulates; Acidic products; Heavy solids build-up; Critical plant safety; Large pressure differentials; Velocity control; Noise control.

Happy Fourth of July from Piping Specialties

"America is much more than a geographical fact. It is a political and moral fact — the first community in which men set out in principle to institutionalize freedom, responsible government, and human equality." 

Adlai Stevenson