What Is a Digital Pressure Switch?
A digital pressure switch is a digital pressure gauge capable of outputting a contact signal to indicate that a certain level of pressure has been reached.
A digital pressure switch is a product that can function as both a digital pressure gauge and a pressure switch at the same time.
7-segment pressure displays and output pressure settings can be set on the panel.
Uses of Digital Pressure Switches
Digital pressure switches are primarily used in production. Specific uses of these switches are as follows:
- For pressure control of vacuum equipment for semiconductor manufacturing
- For in-pipe pressure control in chemical plants
- For pressure management of compressed air receiver tanks
- For press pressure control of hydraulic presses
- For monitoring refrigerant pressure in air conditioners
As an example of use, it is not much different from a digital pressure gauge. However, the main feature of a digital pressure switch is that it can output a contact point. The contact output by pressure can be used to set up interlocks and alarms.
Principle of Digital Pressure Switches
A digital pressure switch consists of a sensor, an arithmetic unit, a display unit, and other components.
1. Sensor Section
The sensor section consists of a pressure sensor and diaphragm. The diaphragm is made of corrosion-resistant stainless steel or silicon. The purpose of the diaphragm is to protect the sensor from the gas or liquid to be observed.
The pressure transmitted from the diaphragm is sensed by a pressure sensor such as a strain gage or piezoelectric element. A strain gage is an element whose resistance changes with pressure, and a piezoelectric element generates a voltage with pressure. The pressure sensed is sent from the sensor to the calculation unit.
2. Arithmetic Section
The arithmetic section is the part that receives analog inputs from the sensor, calculates and outputs the data. A printed circuit board or similar device is used. It digitally outputs the input analog input. At the same time, the analog input is converted and output to the display section.
3. Display Section
The display part visualizes the pressure to be observed; it is generally a 7-segment display using LEDs, and in most cases, the pressure unit is displayed in Pa. Products that allow the decimal point position to be changed are also available.
Types of Digital Pressure Switches
There are different types of digital pressure switches, which are selected primarily by pressure range. The pressure to be monitored is classified into three types: positive pressure, compound pressure, and negative pressure.
1. For Positive Pressure Monitoring
Digital pressure switches for positive pressure monitoring are devices that monitor pressurized conditions. They monitor filter clogging and pump pressure, and are manufactured in a wide range of products for monitoring minute pressure as low as 100 kPa to those for monitoring high pressure as high as 50 MPa. Generally, the upper pressure limit is selected according to the measurement target.
2. For Compound Pressure Monitoring
This device can monitor positive pressure to negative pressure. It is applicable to piping, where positive and negative pressures are intermingled. Refrigerant pressure monitoring for air conditioners is an example.
3. For Negative Pressure Monitoring
This is a device capable of monitoring negative pressure. Also called a vacuum gauge or vacuum switch. It is used to monitor the degree of vacuum in vacuum equipment.
Other Information on Digital Pressure Switches
1. Sensor and Monitor Structure of Digital Pressure Switch
Digital pressure switches are available with either an integrated sensor/amplifier or a separate sensor/amplifier.
Integrated Model
The integrated type is a product in which the sensor and display are combined into one unit. It is characterized by space-saving installation and easy wiring.
Separated Type
Separate type is a product in which the sensor part and the display part are separated. The sensor part can be installed at the measurement location, while the display part, which serves as an amplifier, can be installed at a remote location. This type is used when the measurement location is in a corrosive environment, and the sensitive amplifier and display can be protected. The display section can also be moved to a position where it is easy for people to see.
2. Output Specifications of Digital Pressure Switch
The output specifications of digital pressure switches vary from product to product. Generally, they are classified into semiconductor output and contact output.
Semiconductor Output
The semiconductor output is a digital output by means of a transistor or other means. Although there is no life span based on the number of operations, there is a risk of equipment failure if the wrong type of power supply is used.
Contact Output
A contact output is a physical, electrical contact output. Since it has a drive unit, it has a life span that depends on the number of times it is driven. However, the type of power supply can be selected from a relatively wide range, and it has characteristics such as high resistance to heat.