Using Eductors for Non-Powered Tank Mixing

Eductor for tank mixing
(courtesy of Jacoby Tarbox)

An eductor is a pump that uses a fluid to perform the work of pumping another fluid (or solid). The fluid doing the work is termed the motive fluid, and the fluid being pumped is the suction fluid. The motive fluid employed can be liquid. gas or steam. The suction fluid can be liquid. gas or steam. Other names for eductors include jet pumps, ejectors, Venturi pumps, siphon pumps, steam siphons, and injector pumps. Eductors operate on basic principles of flow dynamics.

Eductors require no power, which means no moving parts. The design of the eductor creates pressure differential allowing fluid to flow naturally within the device - creating suction, mixing, and pushing the liquid throughout the tank.

In-line eductors are the next generation of jet pumps, ejectors, and Venturi pumps providing in-line mixing, pumping, or heating in various process lines. Eductors reduce costs as there are no moving parts and require no direct power.

The video below, while marketing oriented, does a great job at demonstrating how tank mixing is accomplished efficiently and thoroughly with an array of eductors by calculating tank size and volume along with material properties to develop a mixing profile.

For more information, contact:

Mead O'Brien
(800) 892-2769
www.meadobrien.com

The Rack and Pinion Style Pneumatic Valve Actuator

Rack & Pinion Actuator
(courtesy of Flowserve Automax)

Three primary kinds of valve actuators are commonly used: pneumatic, hydraulic, and electric.

Pneumatic actuators can be further categorized as scotch yoke design, vane design, and the subject of this post - rack and pinion actuators.

Rack and pinion actuators provide a rotational movement designed to open and close quarter-turn valves such as ball, butterfly, or plug valves and also for operating industrial or commercial dampers.

The rotational movement of a rack and pinion actuator is accomplished via linear motion and two gears. A circular gear, referred to a “pinion” engages the teeth of a linear gear “bar” referred to as the “rack”.

Pneumatic actuators use pistons that are attached to the rack. As air or spring power is applied the to pistons, the rack is “pushed” inward or “pulled” outward. This linear movement is transferred to the rotary pinion gear (in both directions) providing bi-directional rotation.

Visual of rack and pinion
(courtesy of Wikipedia)

Rack and pinion actuators pistons can be pressurized with air, gas, or oil to provide the linear the movement that spins the pinion gear. To rotate the pinion gear in the opposite direction, the air, gas, or oil must be redirected to the other sides of the piston, or use coil springs as the energy source for rotation. Rack and pinion actuators using springs are referred to as "spring-return actuators". Actuators that rely on opposite side pressurization of the rack are referred to as "direct acting".

Most actuators are designed for 100-degree travel with clockwise and counterclockwise travel adjustment for open and closed positions. World standard ISO mounting pad are commonly available to provide ease and flexibility in direct valve installation.

NAMUR mounting dimensions on actuator pneumatic port connections and on actuator accessory holes and drive shaft are also common design features to make adding pilot valves and accessories more convenient.

Fully automated valve with rack
and pinion actuator, solenoid, and
limit switch.

Pneumatic pneumatic rack and pinion actuators are compact and save space. They are reliable, durable and provide a good life cycle. There are many brands of rack and pinion actuators on the market, all with subtle differences in piston seals, shaft seals, spring design and body designs.

For more information on any pneumatic or electric valve automation project, contact:

Mead O’Brien, Inc.
www.meadobrien.com
10800 Midwest Industrial Blvd
St. Louis, Missouri 63132
Phone (314) 423-5161
Toll Free (800) 874-9655
Fax (314) 423-5707
Email: meadstl@meadobrien.com

Steam Trap Testing Guide for Energy Conservation

Annual steam trap testing schedule

Below is a steam trap testing guide (courtesy of Armstrong International) to maximize efficiency and conserve energy. This guide discusses:

• Steam Trap Testing Procedure 
• Tips On Listening 
• Inverted Bucket 
• Float & Thermostatic Trap 
• Disc Trap 
• Thermostatic Trap 
• Sub-Cooling Trap 
• Traps on Superheated Steam

CAUTION: Valves in steam lines should be opened or closed by authorized personnel only, following the correct procedure for specific system conditions. Always isolate steam trap from pressurized supply and return lines before opening for inspection or repair. Isolate strainer from pressurized system before opening to clean. Failure to follow correct procedures can result in system damage and possible bodily injury.

Steam Trap Testing Guide for Energy Conservation from Mead O'Brien, Inc.