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

Theory of Operation for MOVs (Motor Operated Valves)

Limitorque SMB MOV

This presentation, provided by the NRC, provides an introductory look at motor operated valves, with a focus on the manufacturer Limitorque. The document includes the theory of operation of MOVs, plus descriptions of valve types, such as gate, globe, ball, plug and butterfly.

This document also provides detailed descriptions of Limitorque SMB actuators and Limitorque SB actuators with full assembly and subassembly breakdown and illustrations.

NRC Course on Motor Operated Valves and Limitorque from Mead O'Brien, Inc.

Document provided by NRC.gov

Configuring a Foxboro PH10 Sensor Using the Foxboro 876PH Transmitter

pH and ORP Sensor
(courtesy of Foxboro)

The PH10 DolpHin^® Series pH Sensors and ORP10 DolpHin Series ORP Sensors are suitable for a wide range of pH and ORP measurement applications. They are designed for use with Foxboro^® brand 875PH, 873PH, and 873DPX Analyzers, and 876PH Intelligent Transmitters and 870ITPH Transmitters. Some can also be used with 873APH Analyzers. When used with 875PH Analyzers or 876PH and 870ITPH Transmitters, they provide the additional capability of on-line diagnostics to signal the user if any of several common sensor faults occur.

The sensors are available with a choice of temperature compensation and cable termination. They are available with an internal pre-amplifer for use up to 150 m (500 ft) and with a Smart sensor for use up to 100 m (328 ft) from the analyzer or transmitter. The sensors can be mounted to the process in a number of ways. They have a 3/4-inch external NPT connection on both the electrode and cable end. The sensors can be inserted directly into the process line or tank or mounted through a variety of accessories including bushings, tees, flow chambers, and ball valves/insertion assemblies.The sensors are available in both analog and Smart versions.

These industry-leading sensors are already proven in countless installations including chemicals, pulp & paper, all kinds of industry and municipal water/wastewater treatment, metals/mining, and food and dairy applications worldwide.

The Foxboro^® brand Model 876PH is a 2-wire loop powered intelligent transmitter that, when used with appropriate electrochemical sensors, provides measurement, local display, and transmission of pH, ORP (Oxidation-Reduction Potential), or ISE (Ion Selective Electrode) concentration. The transmitter outputs a HART digital signal and a 4 to 20 mA analog output. Versions are available for use with both analog and Smart (digital) sensors.

This video demonstrates how to correctly configure a Foxboro^® PH10 sensor using the Foxboro^® 876PH Transmitter.

Form ore information, contact:

Mead O'Brien

www.meadobrien.com

(800) 892-2769

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