Powell Fabrication & Manufacturing, Inc.

Gas Safety - Pneumatic Shutdown Systems

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Compressed Gas Valves

Various Cylinder, Ton Container, and Railcar Valves compatible with both Electric and Pneumatic actuators.  More...


UL-CUL Approved

Powell Valve Closure System control panels (UniPro family, MaxPro™ RA & E-Pro®) are listed by Underwriters Laboratory to UL 508A for Enclosed Industrial Control Panels. Panels are listed by Underwriters Laboratory bearing the UL & CUL mark for use in the United States and Canada markets. In applications where a CSA listed control panel in Canada is required, please contact Powell for further information.

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Frequently Asked Questions about the MaxPro™ RA

Chlorine Emergency Shutdown System

Who would benefit from using the MaxPro™ RA?

Answer: Anyone who services small containers (150 lb gas cylinders - one ton containers) of pressurized hazardous gas would benefit from protection against reportable releases.

How much air pressure does the MaxPro™ RA require?

Answer: The MaxPro™ RA will close and seat valves with air pressure from 70 to 120 psig. For ease of opening afterwards and for assurance of sealing even worn valves, Powell recommends 90 psig. At 90 psig, each MaxPro™ RA actuator requires 11.2 cfm of available airflow.

Does the MaxPro™ RA Valve Closure System mount permanently to the container valve?

Answer: No. The MaxPro™ RA actuator is installed temporarily when the gas cylinder or ton container arrives at the process origin and removed once the gas cylinder or container has been emptied. It is then stored at the process origin until the next container is connected to the process.

Can I use the MaxPro™ RA square drive extension to open the gas cylinder or ton container valve after the actuator has been installed on it?

Answer: No. First of all, the MaxPro™ RA valve adapter should be installed with the yoke and gasket as shown in the operating manual. Then, as per industry standards, the valve should be opened carefully by hand using the special Powell wrench as indicated in the instructions in the operating manual. After a leak check has been run and passed, the square drive extension on the MaxPro™ RA actuator can then be used with the special Powell wrench to turn the coupler into alignment with the opened valve stem, and the actuator can be secured on the adapter with the supplied hitch pin.

I have vacuum regulators on the gas cylinders or ton containers that I use. Will the MaxPro™ RA still fit on the gas cylinder or container valves?

Answer: Yes! Piping modifications can be easily made to accommodate vacuum regulators. For more information see "Using Vacuum Regulators with Valve Closure Systems."

The vacuum regulators I use in my process maintain a vacuum in the line from the containers. Why do I need a MaxPro™ RA in addition to my vacuum regulators?

Answer: If a leak occurs at the container valve outlet, the vacuum regulator will not prevent a gas release. Only by closing the actual gas cylinder or ton container valve can a leak from the upstream side of the vacuum regulator be stopped. The MaxPro™ RA responds quickly in this situation by closing the gas cylinder or container valve in less than 3 seconds if a leak is sensed."

How does the MaxPro™ RA know when there is a leak?

Answer: The MaxPro™ RA Control Panel, a component of the MaxPro™ RA system, receives a signal from your gas sensor and sends a signal to the MaxPro™ RA Air Control unit which activates the MaxPro™ RA Actuator, closing the valve.

I service two banks of four  one ton containers each. What kind of a system do I need?

Answer: Before you purchase a MaxPro™ RA Valve Closure System, we will send you a factors sheet that will help us design a system to fit your unique application. The configuration described in this question could be approached in a number of ways, depending on how many containers you want to close at one time. You could have two MaxPro™ RA Control Panels, each operating one MaxPro™ RA Air Control Unit and one bank of 4 containers. In this case, if you chose to close one bank of containers intentionally, the other bank would not have to be closed, yet all of the container valves would still be closed in an emergency. Or, you could have one MaxPro™ RA Control Panel operating one MaxPro™ RA Air Control Unit which would close all 8 containers at one time. The system can be further defined to operate each pair of containers if desired. When you complete the Factors sheet, we will be able to determine exactly what you need.

I service two banks of four  one ton containers each. What kind of a system do I need?

Answer: You'll need a source of 110 VAC power and compressed air or nitrogen at a minimum of 100 psig. If your MaxPro™ RA actuators will be operating outside, you should have air with a dew point of -40 degrees (C or F) at 100 psig to prevent internal corrosion of the actuators.

What if my plant air fails?

Answer: The MaxPro™ RA Air Receiver can be added to the system. It will store enough pressure to activate the system even if your plant air is down.

What if my electrical power fails?

Answer: Powell offers an uninterruptable power supply that will maintain power to the MaxPro™ RA Control Panel and the MaxPro™ RA Air Control Unit in the event of a power outage.

If I have a power failure, my pumps will stop working. Will the MaxPro™ RA Valve Closure System still close the valves?

Answer: Yes! With the help of the uninterruptable power supply, the system can be configured to close the valves when the power goes out or to maintain them open if you desire.

How much torque does the MaxPro™ RA deliver to the valve?

Answer: 40 lb-ft of torque.

Can I open a closed valve without removing the MaxPro™ RA Actuator from the valve?

Answer: Yes. The MaxPro™ RA actuator has a convenient square drive shaft that passes all the way through it for this purpose. However, the container valve should ALWAYS be opened the first time by hand per the industry standards. NOTE: Ton-containers and 150-pound cylinders sometimes arrive with their valves severely over-tightened. Attempting to open these over-tightened valves using the square shaft of the MaxPro™ RA actuator could result in damage to the actuator.

I've seen other valve closure actuators that fasten to the yoke which attaches to the gas cylinder and ton container valve. This looks easier and quicker than the mounting used on the MaxPro™ RA. Why doesn't the MaxPro™ RA actuator mount to the yoke?

Answer: Isaac Newton realized that every action has an equal and opposite reaction. When the competitor's system (which mounts on the yoke) closes the valve, the torque applied to the valve is also applied to the yoke. The result is that after only a few activations, the yoke can become loose on the valve causing a chemical release. By mounting the actuator only on the valve, as is in the case with all Powell Valve Closure Systems, this failure mode is eliminated.

Both the E-Pro® and MaxPro™ RA mount to the valve easily (within seconds) and without any special tools. Backed by Powell's extensive design, durability, and field testing, Powell Valve Closure Systems are superior to any other systems available on the market. When you buy a valve closure system from Powell, you can be assured that you have purchased the most durable and reliable system available.