How Custom Gas Distribution System Design and Fabrication Can Improve Efficiency in Northern Alberta Plants
by Thomas Webster, on Tue, Jun 21, 2022 @ 08:06 AM
Fluid handling facilities depend on effective gas distribution system design to safely and efficiently deliver gases from a high-pressure source to various points of use. These gases are pressurized and can be toxic, corrosive, or flammable. So, careful design decisions are critical to avoid leakage, unplanned maintenance, and downtime, which can lead to inefficient operations or safety hazards. Here, we’ll look at some possible ways your current gas distribution system design may benefit from upgraded components, custom engineering, and ongoing support from your local vendor.
Gas Distribution System Design Basics
Gas distribution systems typically have four subsystems: the source inlet, gas panel, changeover, and point-of-use.
Swagelok Source Inlet (SSI)
The first stage of the gas distribution system design, the source inlet, connects the pressurized gas source to the rest of the system. For a single-cylinder source, it can be as simple as a hose with a cylinder connector. For multiple cylinders or bottles, the source inlet may need to be a more complex system of hoses and valves that deliver gas to the primary pressure control or changeover system.
Like the rest of the gas distribution system design, the engineering details that go into the source inlet depend on the application. Some options include:
- Isolation valves
- Vent or purge for individual lines
- Bottle identification tags
Swagelok Gas Panel (SGP)
The gas panel controls the pressure of gases being delivered and maintains the required flow rate using either a one- or two-stage regulator arrangement. As with the source inlet, the exact design specifications will depend on the gas being handled and individual process requirements.
The pressure regulator is the heart of the gas distribution system, so it’s critical to select the right one for the application. Pressure regulators are selected based on a flow curve like the one shown below. Ideally, a pressure regulator should operate along the flattest part of the flow curve.
The example above illustrates the three parts of a flow curve:
- The ideal operating range, a relatively flat part in the middle.
- The seat-load drop or lockup, where there is an initial steep pressure drop as flow begins.
- The choked-flow area, where the pressure regulator is completely open and no longer regulating pressure.
To ensure reliable and efficient service, the pressure regulator should have a filter to remove solid particles and protect the equipment. The design and material of the filter depend on the gas composition, solids content, pressure, flow, and other system characteristics.
Swagelok Changeover (SCO)
An automatic changeover system seamlessly switches from one cylinder or other gas sources to another when it reaches a set changeover pressure. This controls flow and pressure without ever interrupting the gas supply so the system can operate continuously at a constant pressure.
Changeovers can be semi- or fully automated. An automated changeover saves time and makes the process safer by eliminating human error. Additional safety options are available for hazardous or flammable gas systems.
Swagelok Point-of-Use (SPU)
The point-of-use systems where gas is dispensed are typically the least complex parts of a gas distribution system design. They provide the last stage of pressure control before the gas is used. A point-of-use station typically contains a pressure regulator, pressure gauge, and isolation valve to let operators precisely adjust the gas pressure.
The point-of-use system must provide reliable, consistent operation and be convenient and, above all, safe for the operator. Compact design and custom mounting options can help maximize space and make the system as easy and safe to use as possible.
Safety and Efficiency Design Considerations
Gas distribution systems frequently carry hazardous gases, making safety the top priority. To prevent harm to operators, equipment, and the environment, a gas distribution system design must account for any potential hazards and mitigate the risks as much as possible.
Here are a few safety considerations for any gas distribution system design:
- Reduce potential leak points by minimizing the number of connections.
- Make maintenance and troubleshooting easier by making all components and panels easy to access.
- Keep components organized and clearly label them to prevent errors.
Special Considerations for Oxygen Systems
Oxygen systems present a particularly significant fire risk. Gases or safe materials in atmospheric oxygen levels may ignite in an oxygen-enriched environment.
The “fire triangle” above shows the three elements needed to ignite a fire: oxygen, fuel, and heat. Normally, fires can be prevented by removing or limiting one or more elements, but oxygen and fuel can’t be removed from an oxygen handling system.
By making good decisions with your initial gas distribution system designs, you can improve the safety of oxygen systems by eliminating sources of heat and other hazardous conditions. Some ways to do this include:
- Avoid using stainless steel piping or tubing. Oxygen systems should be made of special materials like brass or ceramic.
- Avoid using any type of flammable oil or grease in the system.
- Use only smooth-bore tubing.
- Use only valves designed for oxygen service. While fast-acting ball valves are a good fit for most systems, they can cause pressure spikes and potentially hazardous conditions.
- Ensure pressure control valves are sized so that they can handle the system’s full range of pressures and flows.
Let the Experts Optimize Your Gas Distribution System Design
Whether you’re installing a new gas distribution system or upgrading an existing one, Edmonton Valve & Fitting is here to help. Our Field Advisors can evaluate your existing gas distribution systems and recommend quality Swagelok components that can improve safety and efficiency. We can also help engineer an optimized gas distribution system from the ground up for any gas handling application. We provide standardized, modular systems and industry-leading Swagelok components customized to your application.