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What Are Rack and Pinion Actuators?

Operation rack and pinion actuator.

Rack and pinion actuators convert linear movement of a driving mechanism to 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.

There are 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.

How Rack and Pion Actuators Operate

Image courtesy of Wikipedia

The rotational movement of a rack and pinion actuator is accomplished via linear motion and two gears. A circular gear, known as a “pinion” engages the teeth of one or two linear gears, 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 changes position. This linear movement is transferred to the rotary pinion gear (in both directions) providing bi-directional rotation to open and close the connected valve.

Rack and pinion actuators pistons can be pressurized with air, gas, or oil to provide the linear the movement that drives the pinion gear. To rotate the pinion gear in the opposite direction, the air, gas, or oil must be redirected to the other side of the pistons, 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".

Internal view of rack and pinion actuator

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.

Rack and pinion
actuator with valve.
(Flowserve Worcester) 

Pneumatic pneumatic rack and pinion actuators are compact and effective. They are reliable, durable and provide good service life. 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. Some variants are specially designed for very specific operational environments or circumstances.

Share your process valve control and automation challenges with application experts, and combine your process experience and knowledge with their product application expertise to develop effective solutions.

Macnaught Now Offers Explosion Proof/Flame Proof (Ex D) Sensors for Hazardous Areas on MX-Series

Macnaught MX Series

Macnaught’s Positive Displacement Flow Meters are suitable for a wide range of industrial applications including fuel and oil distribution, corrosive chemical, solvent measurement and high pressure applications to name a few.

Macnaught is proud to now extend its range of pulse output options to include Ex D flame proof approved sensors for hazardous areas.

Download the MX-Series Explosion Proof/Flame Proof (Ex D) Sensors for Hazardous Areas cut sheet here, or review the embedded document below. For more information on Macnaught flowmeters, contact Ives Equipment by visiting https://ivesequipment.com or call (877) 768-1600.

Explosion Proof/Flame Proof (Ex D) Sensors for Hazardous Area Now Available in Macnaught MX-Series from Ives Equipment

Alfa Laval UltraPure Pumps: LKH UltraPure, LKH Prime UltraPure, SolidC UltraPure, SX UltraPure

Alfa Laval UltraPure pumps are specifically designed for the toughest, most demanding pharmaceutical applications. Their design pays a high level of attention to hygiene and repeatability to reduce the risk of contamination and delivers maximum energy efficiency, a reduced C02 footprint, higher yields and increased uptime.

LKH UltraPure

Designed to meet the specific demands of the biotech and pharmaceutical industries, LKH UltraPure centrifugal pumps deliver maximum uptime and high efficiency plus the benefits of easy cleanability.

LKH Prime UltraPure

The LKH Prime UltraPure is an efficient, versatile self-priming pump designed for Cleaning-in-Place duties containing entrained air with the ability to also pump product in pharmaceutical industry.

SolidC UltraPure

The special features of SolidC UltraPure centrifugal pumps include an external shaft seal and spring, a defined-compression O-ring on the back plate and crevice-free design.

SX UltraPure

Alfa Laval’s premium rotary lobe pump designed for gentle transportation of process fluids in high purity applications in the biotechnology and pharmaceutical industries.

https://iveequipment.com
(877) 768-1600

Five Key Reasons You Should Consider Oval Gear Flow Meters

Oval gear flow meters are simple and robust. They operate by interlocking two oval gears, offset by 90 degrees, inside the meter housing which are then rotated by the flowing media. They are very rugged and designed to operate in very harsh environments. Accuracy is maintained irrespective of temperature, viscosity change, or flow pulsation. It's not unusual to see these meters perform in the field for 30 to 40 years.

Internal view of oval gear flow meter (Macnaught)

Five Reason You Should Consider Oval Gear Flow Meters

1. No flow conditioning - put the meter where you want it. Locate off pumps, valves, U bends with no loss in accuracy or repeatability.
2. Compact meter footprint allows for excellent OEM or MRO install challenge solutions
3. Accuracy is unaffected by viscosity changes.
4. Heavy Duty - meter construction is designed for vibration, dust, piping hammer, low & high ambient temperature conditions -40F to 302F.
5. Outstanding flow turndown gives best cost of ownership meter sizing potential.

For more information on oval gear flow meters, contact Ives Equipment by visiting https://ivesequipment.com or calling (877) 768-1600.

Valves and Automation for Hygienic, High Purity, or Sanitary Use

The following document presents Alfa Laval's Hygienic (sanitary, high purity) valve offering, including:  Unique Mixproof valves; Unique Mixproof tank valves; PMO (Pasteurized Milk Ordinance) Mixproof series; Tri-Clover Unique 7000 single seat valves; LKB butterfly valves; UltraPure valves; Aseptic diaphragm valves; Ball valves; Control valves; and Regulating valves.

You can review the embedded document below, or download your own PDF version of Alfa Laval Valves and Automation for Hygienic here.

Valves and Automation for Hygienic Use from Ives Equipment

Basics of Thermocouple Junction Design

Industrial thermocouples (AST)

Thermocouples are simple devices made up of several key components: thermocouple wire, electrical insulation, and the sensing junction. Many thermocouple designs also include a stainless steel sheath that protects the thermocouple from vibration, shock, and corrosion.

A thermocouple has three variations of sensing tip (or junction):

• Exposed junction, where the exposed wire tips and welded bead have no covering or protection.
• Grounded junction, where the welded bead is in physical contact with the thermocouple's sheath.
• Ungrounded junction, where the tip is inside the thermocouple sheath, but is electrical (and somewhat thermally) insulated from the sheath (no sheath contact).

Exposed junction thermocouples respond to temperature change quickly and are less costly, but their signals are susceptible erratic reading caused by induced or conducted electrical noise. Because there is no sheath, they are also prone to mechanical damage and ambient contamination.

Grounded junction thermocouples provide fast response and are mechanically more robust, with a metallic sheath that protects the thermocouple both mechanically and from contaminants. But because their sensing tip is in contact with the external sheath, their signal still can be affected by externally induced or conducted electrical noise.

Ungrounded thermocouples, like grounded, are protected mechanically and from ambient contaminants by their sheath. However, their sensing junctions are kept separate from their metallic sheath, isolating the junction from external electrical  interference. This separation does come at a small cost in temperature sensing responsiveness though.

For safety, precision, and optimum performance, always talk to an applications specialist when applying temperature sensors. A short phone call can prevent major headaches and lost time in  troubleshooting a misapplied thermocouple.