Limit Switch box 

1. What is the Limit Switch box？

The Limit Switch box is a field instrument for detecting the status of valves in automatic control systems. It is used to output the opening or closing position as a switch signal and is received by a remote controller or sampled by a computer search. After confirmation, the following procedure is executed. The product can also be used as an essential valve chain protection and remote alarm indication in the automatic control system.

The Limit Switch box is a mechanical housing mounted on a valve package. These are typically used for switching globe valves in valve packages.

Valve positioner indicators are electrically switched devices installed directly on the valve actuator or independently on the distributor box. They are used in conjunction with valve positioners.

2. What are the alternative names of Limit Switch boxes？

There are several expressions for Limit Switch boxes that are synonymous in the industry and are used to be interchangeable.

Some of the more common terms are as listed：

☆Limit switches box

☆Beacon

☆Valve position indicators

☆Valve position transmitter

☆Switch boxes

3. What are the working principle of the Limit Switch box？

It is a commonly used small current mains electrical apparatus. It uses the collision of moving parts of production machinery to actuate its contacts to turn on or break the control circuit for certain control purposes. Typically, these switches are used to limit the position or travel of mechanical movements so that the moving machinery is automatically stopped, reversed, variable speed, or automatically moved back and forth in a particular position or travel.

Electrical control systems are used to achieve sequence control, positioning control, and position status detection. In addition, it is used to control travel and limit the protection of machinery and equipment.

In actual production, it will be installed in a pre-arranged position. When the module mounted on the moving parts of the production machinery hits the travel switch, the resulting contact action realizes the switching of the circuit.

4. What are the primary functions of theLimit Switch box？

I.Position indication by local vision – allows personnel to determine the position of a valve quickly and easily using a visual indicator on the top of the visual position indicator housing.

II.Electrical feedback from interior switches, sensors, transmitters, and other similar devices provide the valve position to the PLC or control room by sending an electrical signal which contains a position code.

III.A local terminal box, which can be utilized to close the position switch, offers a deck to install the solenoid valve and provides a termination point to connect the appropriate signal line to the enclosure.

5. What are Limit Switch box  Specifications？

Valve positioner indicators vary in the type of display, the number of indicated positions and switches, and the specifications for poles and throws. Shaft diameter and working temperature are extra factors to consider. Most vendors designate the diameter of the shaft in English units like inches (in) or metric units like centimeters (cm). Working temperature is measured in degrees Fahrenheit (°F) or Celsius (°C).

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SomeLimit Switch box s show information on a rotating dial or sliding scale. Others have a light-emitting diode (LED) indicator. There are also limits Switch box s with position transmitters. These devices offer continuous, signal-based information about the valve’s open, closed, or intermediate position.

Number of Indicated Positions

The number of position indications shows the level of valve position indicated by the valve position indicator.

Two-way devices offer a primary open/closed indication.

Three-way, four-way, 120°, and 180° indicators give more command over the indicated position of the valve.

Continuous indicators supply the full scope of valve position.

Pole and Throw

There are a few different poles and throw classes.

Single Pole Single Throw (SPST) switches enable or disable a single conductor in a single branch circuit.

Single Pole Double Throw (SPDT) switches have two terminals and connect or disconnect a single conductor to two other single conductors.

Double-pole single-throw (DPST) switches have four terminals to enable or disconnect two circuit conductors in a single branch circuit.

Double Pole Double Throw (DPDT) switches have six terminals for connecting or disconnecting two separate circuits.

Specific as below：

◆ The three-dimensional position indicator clearly shows the position of the valve.

◆ Die-cast aluminum alloy casing has a powder-coated, compact design with an attractive appearance, reduced valve packaging volume, and reliable quality.

◆ Double line interface Double 1/2 NPT pipe interface.

◆ Signal feedback device.

◆ The indicator can identify the switching position.

◆ Multi-contact internal wiring board Internal 8 contact wiring board meets the standard of a micro switch, DPDT switch option, proximity switch, magnetic switch option, and can be used to connect solenoid valves.

◆ “Quick position” cam; the adjustable cam of the ITS-100 limit switch is mounted using splines and springs; the position of the switch cam can be quickly adjusted without tools.

The PCB board is used instead of wiring to prevent short circuits.

◆ Ambient temperature: -25 to 85°C, protection class: IP67, optional IP68, explosion-proof class: ExdII BT6, Exd IICT6, by EN50014/50018.

◆ Double connection port, standard contact, safe and convenient wiring.

◆ Easy to install the bracket with four types of stands. The frame, according to ISO5211 standard, any rotating actuator can be easily installed.

The bolts are attached to the top cover and will not come off when disassembled.

◆ Corrosion-resistant.

External coating: polyester coating (black).

◆ Bracket material is available in SS304.

◆ Available in standard and explosion-proof versions.

6. What are the features of limit Switch box s？

The electrical on/off rated values, axis/installation options, and optional functions are key concerns when selecting a limit switch box.

The electrical on-off current ratings include maximum AC rated current, maximum DC rated current, maximum AC rated voltage, and full DC rated voltage.

Mounting can be provided on standard or special shafts.

Intrinsically safe (IS) is a protection technology for the safe performance of electronic equipment in explosive environments.

Explosion-proof products can withstand hostile conditions such as blasting.

Chemically or corrosion-resistant products can survive difficult situations, such as exposure to chemical or corrosive materials.

NetworkableLimit Switch box s can be connected to a vast network and supervised by other equipment.

7. What are the advantages of the limit switch box？

Robust and compact design.

Robust aluminum die-cast housing with built-in 2-loop double-break type switch. Damage-proof and reliable circuit breakers.

Excellent environmental resistance.

A wide range of general-purpose and explosion-proof versions, including cold, heat, corrosion, and weather-resistant versions, are available.

Extremely long life.

Reduced friction on the sliding part and corrosion resistance provide a mechanical life of more than three times that of older models in field environments (mechanical life of 30 million cycles or more), significantly reducing the number of sudden stops.

Explosion-proof.

We have an IEC explosion-proof outdoor gas and steam explosion-proof product, safe and highly explosion-proof. Ex-proof construction (Exide IIC T6) for use in hydrogen environments. We have a wide range of products with various certifications such as ATEX and IECEx.

Corrosion-resistant.

The externally exposed parts are all stainless steel for complete corrosion resistance.　As a result, they can be used under severe conditions (up to 10m water depth) in harbor equipment, pharmaceutical-related equipment, and water treatment-related equipment.

Easy to install

Well-designed bracket connection holes, the switch can be mounted separately for easy maintenance and replacement.

Can be set without tools and no further adjustment after the initial setting

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8. What’s the industrial use of limited Switch box s？

TheLimit Switch box is mainly used to convert mechanical displacements into electrical signals that allow the operating state of the motor to be changed, thus controlling mechanical movements or for program control.

The most used is in industry, where it is used in conjunction with other devices to form more complex automation equipment.

There are many of these on machine tools, where it is used to control the movement of the workpiece or the stroke of the automatic tool feed to avoid collisions. Sometimes it is used to make the controlled object change direction automatically between two defined positions, thus obtaining a constant reciprocating movement. For example, the automatic material transport trolley reaches the endpoint and touches it, connects to the tipping mechanism, tilts the material out of the car, and returns to the starting point. When it reaches the starting point, it touches the travel switch at the starting point again, which switches on the circuit of the loading mechanism and starts loading the trolley automatically. It is an automatic production line that works day and night without human intervention, saving human labor.

9. What’s the application of the Limit Switch box？

TheLimit Switch box is a wide range of limit switches that can be used in a variety of settings. They are widely used in general industrial machinery, various industrial plants, outdoor equipment, specified explosion-proof equipment, etc. High-temperature environments, low-temperature environments, salt environments, etc. The optimum limit switch can be selected according to the application.

It can also be widely used to control and limit the spatial three coordinates of lifting and transmission machinery in the construction, port, and mining industries. It is widely used in construction machinery because of its small size, multiple functions, high precision, adjustable limits, strong versatility, easy maintenance, installation, and adjustment.