A pressure switch is a mechanical or electronic device that springs into action when a particular pressure threshold or setpoint is reached. These failsafe response components tell the system to perform an action if a specific pressure threshold is met.
For example, pressure switches can be used to ensure sufficient flow is going through a system (e.g., enough air flowing through an air filter). They can also be used to guarantee patient safety in medical applications, for example, certifying that a ventilator does not apply too much pressure when providing air to a patient’s lungs.
Historically, these switches were mechanical in nature; however, technological advancements are seeing mechanical switches being phased out in favor of electronic controls. There are a number of reasons for the shift to electronic pressure switches, including:
- Faster adjustments, resulting in improved response times and accuracy
- Field programmability
- Greater reliability and easier to service
- Improved usability and more ‘plug and play’ setup
- Increased operating flexibility
Figure 1. Mechanical vs. Electronic Pressure Switch. Image Credit: Superior Sensor Technology
Pressure switches are applied in many different scenarios. With regards to air and gases, some of the most frequently used devices that integrate pressure switches within the medical and HVAC industries are:
- Medical ventilators: Ventilators utilize pressure switches to substantially reduce patient hazards by sounding alarms (or shutting down systems) if the pressure applied to the patient is too great.
- Positive Airway Pressure devices: CPAP, BiPAP and APAP devices are used for the treatment of a number of respiratory conditions such as asthma, COPD, and sleep apnea. Like with ventilators, pressure switches are used to considerably reduce patient hazards if too much or too little air pressure is being applied.
- Oxygen Concentrators: Oxygen concentrators increase oxygen levels while reducing the level of nitrogen in the air. Pressure switches sound warnings in the event of error or over-pressure.
- Air filtration: Air filtration systems prevent dust and other particles from being pumped into the air. A pressure switch serves as an alarm to draw the technician’s attention to when the airflow pressure drops below a certain threshold, signaling that it is time to clean or replace a dirty filter.
- Airconditioning vents: Throughout an ‘airflow network,’ air vents are the endpoints where air reaches the room it is trying to cool or warm. Pressure switches can be installed within the vents to cause an alarm if the vent is starting to clog.
Types of Pressure Switches
There are fixed and variable types of electronic pressure switches:
Fixed Pressure Switches
As their name suggests, fixed pressure switches are pre-configured to a non-variable pressure threshold as set by the manufacturer. The device maker takes possession of the pressure switch with preset, fixed values. Examples of applications where fixed pressure switches are frequently used include certain types of medical devices, such as ventilators.
Variable Pressure Switches
Variable pressure switches allow the threshold value to be set by the device maker or a user in the field. If controlled by the device maker, when assembling the product, they select specific resistor pairs that control the voltage input that specifies the threshold. Once the device has been assembled, it is no longer possible to change the threshold.
In cases where the threshold can be set by field users, software or mechanical knobs/switches are frequently deployed. In this case, the pressure switch is not usually implemented as a safety feature. A prime example is with air filters – where, depending on the system implementation, the threshold value can be adjusted to account for any head loss in the flow stream.
The NimbleSenseTM Pressure Switch
Incorporated into all of Superior Sensor Technology’s differential pressure sensors, NimbleSense architecture is a sub-system that combines processing intelligence with signal path integration and proprietary algorithms to generate modular building blocks that can be easily selected to facilitate a wide range of applications.
One of the key building block features in NimbleSense is a pressure switch capability that is directly integrated into the pressure sensor.
As with other comparable pressure switches, Superior Sensor’s pressure switch flows between states depending on whether the measured pressure is above or below a specific threshold. This can be used as a rapid response failsafe feature for overpressure conditions and to deliver other simplified on/off system feedback.
However, as opposed to other more common pressure switches, the Superior Sensor pressure switch incorporates three modes for setting threshold pressure, one fixed and two variable:
- Fixed mode: Superior Sensor Technology determines the threshold and offers the device manufacturer a ‘ready to use’ preconfigured sensor (with an integrated pressure switch).
- Variable mode 1: The device manufacturer has the option to configure and set the proper thresholds during product manufacturing.
- Variable mode 2: Pressure thresholds are user programmable in the field using the software so that the pressure switch can be ‘fine-tuned’ post-product manufacture depending on the use case.
The three modes offer manufacturers full implementation flexibility. Furthermore, as an intrinsic part of the pressure sensor, there is no need to add an external switch to the Superior Sensor pressure sensor, thereby:
- Eliminating the cost of an external pressure switch
- Reducing product PCB space requirements
- Lowering system-level power consumption
System Benefits
The NimbleSense pressure switch capability can deliver advantages to electromechanical products, including CPAP/BiPAP/APAP, HVAC systems, medical ventilators, oxygen concentrators, anesthesia machines, and numerous other industrial devices.
At the systems level, the NimbleSense pressure switch offers a number of benefits:
- Streamlines product design with an integrated approach
- Accelerates time to market by eliminating the need to add in an external pressure switch
- Reduces system costs by removing the need to add extra components
- Offers maximum design flexibility due to its three modes for setting threshold pressure
Availability
Superior Sensor’s pressure switch capability is available across the following product lines:
If an application is likely to benefit from a built-in pressure switch, contact Superior Sensor Technology today to discuss how best to introduce the NimbleSense pressure switch capabilities.
This information has been sourced, reviewed and adapted from materials provided by Superior Sensor Technology.
For more information on this source, please visit Superior Sensor Technology.