Safety Relief Valves: The Basics

Safety relief valves by Kunkle

The safety relief valve is used to control or limit the buildup of pressure in a piping system, tank or vessel. Uncontrolled pressure can occur because of valve malfunction, process system upset, instrument failure, or fire.

In generally accepted practices, pressure build-up is relieved by allowing the fluid to flow from an alternate path in the piping system. A safety relief valve is engineered so that it opens at a predetermined pressure setpoint to protect vessel, piping or ancillary equipment equipment from being subjected to pressures that exceed their design limits.

When process pressure is exceeded, a safety relief valve becomes the “weak link”, and the valve opens to divert a portion of the fluid to another path. The diverted liquid, gas or liquid–gas mix is usually routed through a piping system to a process where it is safely contained or burned off via a flaring system. Once the liquid or gas is diverted, the pressure inside the vessel drops below the safety relief valves' re-seating pressure, and the valve closes.

The Data Supplement below presents a wealth of technical information on Kunkle relief valves.

Data Supplement for Kunkle Safety and Relief Products from Mead O'Brien, Inc.

A Modern Industrial Hot Water System Saves Money Through Efficiency and Safety

State-of-the-art hot water heating systems
improve efficiency and safety, and
increase production and yield.

The use of hot water systems for process heating pre-dates World War II, and initiated an ongoing effort for engineered materials to accommodate higher pressures and temperatures. After WWII the need for instantaneous hot water generation, distribution and precise temperature control for industrial applications continued to rise. High temperature hot water systems became increasingly popular because they were relatively inexpensive to install, provided long operating life, and were inexpensive to operate and maintain. Their closed system design made these systems more tolerant to corrosion and scale, while the use of pumps eliminated the need for complex piping for managing condensate.

By developing a comprehensive strategy that includes state-of-the-art water heaters, water temperature controls, hose stations, variable frequency drive (VFD) pump assemblies and ancillary accessories such as storage tanks, and pressure-reducing valves, processing plants can improve efficiency and safety, and increase production and yield.

Advanced hot water heating systems typically include:

• Steam/water hot water systems with digital control technology and instantaneous heat exchanger design—shell and tube or plate and frame.
• Industrial mixing center with digital control valves, pre-piped as an IMC with requisite installation components for compact design and ease of installation.
• Digital control valves for delivering hot water immediately on demand, and maintained at precision temperatures (+/-1°F, +/-0.5°C).
• VFD pump assemblies application-engineered and configured for your site.
• Hot & cold water hose stations with thermostatic mixing valves that replaces the old, basic Y as the temperature controller.

The brochure below, courtesy of Armstrong International, provides more insight where specific components are used.

Hot Water for Industry from Mead O'Brien, Inc.

Triple Eccentric Disc Valve, Metal Seated, with Flow Balancing Trim

Neles Triple Eccentric Disc
Valve, Metal Seated with
Flow Balancing Trim

TRIPLE ECCENTRIC SEATING PRINCIPLE

The disc of the valve is machined to close tolerances to create an elliptical shape similar to an oblique slice taken from a solid metal cone. When the valve is closed, the elliptical disc at the major axis displaces the seat ring out- ward, causing it ring to contact the disc at the minor axis. When the valve is opened, the contact is released and the seat ring returns to its original circular shape.

CONTROL STABILITY AND SUPERIOR TIGHTNESS

The S-DISC® control valve unit provides outstanding control performance and excellent long-lasting tightness in the same valve. The very simple and robust construction guarantees long trouble-free operation and maximum reliability.

The S-DISC design consists of a standard NELDISC® triple eccentric disc valve equipped with a flow-balancing trim. The trim has been located on the downstream side of the valve body. The ingenious idea of this design is to transfer fluid forces out of the disc to the body. 

Figures 2 and 3 illustrate the flow treatments with a concentric-type conventional butterfly valve compared to the S-DISC-design. The S-DlSC design offers stable flow control and reduced dynamic torque, noise level and vibrations. The dynamic behavior of the valve is very smooth and stable, which means less load on the shaft bearings, less required torque, smaller actuators and more economical control unit total costs. All of the excellent features of the standard NELDISC are available.

The most standard NELDISC can be easily modified to the S-DISC design, just by changing the flange ring.

FEATURES

• Excellent flow and control performance.
• Wide temperature range from -200 ... +600 °C /-330 ... +1110 °F.
• Reduced dynamic torque and noise.
• Mechanical and flow dynamic stability allows higher pressure drop service than a conventional disc.
• ASME 150/PN 20, ASME 300/PN 40 and ASME 600/
• PN 100.
• Sizes DN 80...1500/3"...60"

For more information, visit http://www.meadobrien.com or call (800) 892-2769 for immediate service.

A Magmeter Designed to Withstand the Most Common Failure Modes

Foxboro magnetic flowmeter and transmitter.

When it comes to the application of Magmeters, the biggest problem our customers have is reliability. These devices commonly breakdown due to the corrosive and abrasive materials they measure, and the effects of the internal pressure of the liquid flowing through them.

Foxboro magnetic flowmeters, however, solve these industry-wide issues with superior construction, compact design, the widest selection of options, combined with low power consumption.

Foxboro magnetic flow tubes utilize a superior electrode. By using large electrodes, the flowmeter output is less sensitive to the effects of entrained air, and unaffected by higher internal pressures.

Rugged Teflon liners are resistant to chemical attack which makes it possible to use the Foxboro magnetic flowmeter in hard to handle corrosive liquids and slurries.

Finally, Foxboro magnetic flowmeters offer system  accuracy of plus or minus 0.25 percent of reading.

Foxboro flow tubes can be paired with there IMT 25 and IMT 96 transmitter for complete compact system that provides unequalled durability measurement accuracy and performance with virtually no maintenance and minimal replacement cost covering the widest choice of industry applications available.

For more information on Foxboro magnetic flowmeters please contact Mead O'Brien at (800) 892-2769 or visit http://www.meadobrien.com.