ultra low pressure transducer

The low differential pressure sensor is a typical sensor, which has certain applications in various industries. It is also a commonly used sensor. The following is an introduction to the working principle of the low differential pressure sensor.

The two pressures of the measured medium of the low differential pressure sensor enter into the high and low pressure chambers, and act on the isolation diaphragms on both sides of the δ element (that is the sensitive element). Then they are transmitted to the both sides of measuring diaphragms through the isolation diaphragms and the filling liquid in the elements. The electrodes on the measuring diaphragms and the isolation diaphragms on both sides constitute a capacitor respectively.

When the pressures on both sides are inconsistent, the measuring diaphragms will be displaced, and the displacement is proportional to the pressure difference, therefore, the capacitance on both sides is not equal, which is converted into a signal proportional to the pressure through the oscillation and demodulation link. The working principle of pressure transmitter and absolute pressure transmitter is the same as that of differential pressure sensor, the difference is that the pressure in the low pressure chamber is atmospheric pressure or vacuum.

low cost pressure sensor

No matter what the transmitter is, there will always be some unavoidable problems in the process of using, such as the inevitable errors of the differential pressure transmitter. And we are able to consider comprehensively when choosing the differential pressure transmitter, such as the accuracy and linearity of the differential pressure transmitter, so as to avoid the errors of the differential pressure transmitter as much as possible. Generally, there are four unavoidable errors in differential pressure transmitters, and a brief introduction is as follows.

1. Linear error: This is a factor that has less influence on the initial error of the dp pressure transmitter. The cause of the error is the physical non-linearity of the silicon chips. However, for the transmitter with amplifier, it should also include the non-linearity of the amplifier.

2. Offset error: Since the vertical offset of the differential pressure transmitter remains constant throughout the pressure range, the variations of the transmitter diffusion and laser adjustment correction will produce offset errors.

3. Hysteresis error: In most cases, the hysteresis error of the differential pressure transmitter can be completely negligible, because the silicon chips have a very high mechanical rigidity. In general, only the hysteresis error needs to be considered in the case when the pressure changes greatly.

The above three errors are unavoidable. Now can only try to choose a differential pressure transmitter, of which the precision that is suitable for oneself. Using good production equipment and technology to reduce these errors and it is also possible to perform error calibration before leaving the factory to minimize the impact of errors.

cost effective pressure transducer

There are multiple types of pressure transducers for a variety of applications. Each pressure transducer has different aspects that will impact how it works and the applications the pressure transducer works best for. When selecting a pressure transducer, keep these five criteria in mind:


1.Pressure range:

First of all, it is important to choose a sensor with a measuring range that corresponds with the pressure range you need to measure, taking into account normal conditions and possible occasional pressure variations.Alpha provide Unidirectional minimum range is 0-25Pa(0-0.1 in.WC)  and maximum range is 0-25000Pa(0-100 in.WC) ;Bidirectional minimum range is -10Pa to 10Pa(-0.05 to 0.05 in. WC) and maximum range is -10000Pa to10000Pa(-50 to 50 in. WC)


Long-term stability is one of the most important parameters that determine the overall measurement accuracy of a pressure sensor. Long-term stability in pressure sensors is defined by the maximum acceptable change in zero and span values during the course of the calibration interval of the sensor. In short, for a sensor to be considered stable, it should maintain a very low drift in its measurements over the calibration interval. Alpha stability is ±0.5% FS/YR which higher than most of the others.

3.Over pressure

Overpressure refers to the maximum pressure value a transducer can withstand without affecting performance; it can also refer to a situation where the pressure value exceeds the limits. Although it is not ideal, pressure transducers can withstand occasional pressures up to their overpressure rating, eventually returning to their natural state. However, pressures that reach burst pressure, the maximum pressure that may be applied to the positive pressure port without physically damaging the internal sensing component, can rupture the diaphragm and cause leakage. Pressures above overpressure but below burst pressure can result in permanent diaphragm deformation, causing an output shift affecting operational performance or accuracy readings.

  1. Accuracy

Pressure gauges come in many different accuracies. Accuracy of common pressure transducers could range from 0.5% to 0.05 % of the full-scale output. While Alpha focus on high accuracy from 0.6%-0.25% for very low pressures for critically demanding applications.


5.Compensation range

The compensated temperature range defines the limits of operation for specified measurement accuracy.  e.g. A pressure sensor has an accuracy of 0.25% full scale over a compensated temperature range of -20 to +80 degC.

Since temperature errors are often significant for many measurement devices, a manufacturer will incorporate digital or analogue temperature compensation.  If the measurement device is used outside the compensated temperature range, the accuracy statement is no longer valid, because the device has not been tested or compensated for that temperature.

6.Why choose a capacitive pressure sensor

In a  capacitive pressure sensor, the membrane is one of the capacitor plates. Under pressure, the membrane deforms, varying the capacitance of the capacitor. These sensors provide a good level of accuracy and sensitivity, they can measure low pressures, in the mbar range.

cost effective pressure sensor

Now there are a variety of pressure sensors on the market for equipment engineers to choose from. Among them, capacitance and Piezoresistance pressure sensors are the most widely used.

Capacitance pressure transducer is a kind of pressure sensor which uses capacitance as sensitive element to change the measured pressure into capacitance value. Capacitive transducer for pressure measurement generally uses a circular metal film as an electrode of the capacitor. When the film is deformed due to pressure, the capacitance formed between the film and the fixed electrode will change, and the electrical signal related to the voltage can be output through the measuring circuit.

Piezoresistance pressure sensor is mainly based on piezoresistive effect. Piezoresistive effect is used to describe the resistance change of materials under mechanical stress. The pressure of the measured medium acts on the diaphragm of the sensor directly, which makes the diaphragm produce a micro displacement proportional to the pressure of the medium, and changes the resistance value of the sensor. The change is detected by an electronic circuit, and a standard measurement signal corresponding to the pressure is converted and output.

Piezoresistance Sensor Capacitance Transducer

·The earliest and most widely used type of pressure sensor.

·simple construction, low cost and good durability.

·Sensors must be powered, which makes them unsuitable for low-power or battery operating systems.

· When measuring the micro differential pressure within 10KPA, the sensitivity and accuracy are not high enough, and it is easy to drift。



· Because there is no direct current flowing through the capacitors, they are essentially low-power.

·The capacitor elements are mechanically simple and robust and are very adaptable to overpressure conditions.

·Ideal for low voltage applications and quite harsh environments.

·Capacitance Transducer has low hysteresis and good repeatability. The temperature sensitivity is also very low.


Intrinsically Safe refers to the function of making the production equipment or production system itself safe by means of design, which will not cause accidents even in the case of misoperation or failure. Specifically, it includes failure-safety (misoperation will not cause accidents or prevent misoperation automatically), failure-safety function (equipment and process can work normally temporarily or change safety state automatically in case of failure).

Intrinsically safe electrical equipment is characterized by the fact that all its circuits are intrinsically safe, that is, in normal operation or under the specified fault state the electric spark and thermal effect can not ignite the specified explosive mixture of the circuit. In other words, this kind of electric appliance is not explosion-proof by outer shell and filling, but the energy of electric spark or thermal effect produced by its circuit during normal use or failure is less than 0.28mJ (B-class explosion-proof), that is, the gas concentration is 8.5% (the most explosion-prone concentration), the minimum ignition energy.

The theoretical basis of Intrinsically Safe is to ensure that the electrical and thermal energy in the system is low enough not to cause the combustion of explosive gases, so only low voltages and small currents are allowed to flow through the hazardous area, and there are strict limits on energy storage.

Alpha offer Intrinsically Safe Pressure Transducer

The Model 168 intrinsically safe pressure transducer USES a metallic aluminum enclosure and complies with NEMA Level 4 (IP-65) standards

At the same time the product has the intrinsically safe explosion-proof function, very solid and reliable.


surface mount pressure sensor

Keeping Isolation rooms Safe During Disease Outbreaks

The outbreak of an infectious disease can be overwhelming if a hospital is not prepared. Hospitals employ a variety of strategies to prevent the spread of such illnesses. One of the most prevalent approaches is to treat these patients in isolation rooms. For those working in and around isolation rooms, their safety depends on proper control of the differential pressure of the room. As the coronavirus becomes ever more a pressing concern, it is critical for hospitals and staff to take the right precautions for keeping isolation rooms safe.

What are Isolation Rooms?

Isolation rooms are designed to prevent contaminated particles from spreading beyond a quarantined area. To prevent the contaminated air from escaping, isolation rooms require negative air pressure relative to the outside reference area, a difference of at least -0.01” WC. This ensures clean air is drawn into the room and contaminated particles, such as cough droplets, inside the room are not able to escape.
A relevant example of an infectious disease currently being treated in isolation rooms is the coronavirus. Since coronavirus can be easily spread through the air, treating patients in an isolation room keeps staff and other hospital patients safe from contracting the disease.
Although an isolation room might have the equipment necessary to meet minimal safety standards, such technology is often outdated and has disadvantages that can put patients and staff at risk. In an outbreak such as coronavirus, upgrading old instruments to eliminate said drawbacks can help ensure the safety of an isolation room. Improper or unbalanced room pressurization can put patients and staff at risk of exposure if dangerous contaminants escape the space.

How to Better Maintain Safety of Isolation Rooms

Hospitals are often fiscally constrained from making facility upgrades; yet, now more than ever, the healthcare system needs to demonstrate it can handle a potential epidemic, especially as the risk of coronavirus looms.
The most resourceful way to implement an isolation room strategy is to utilize the real-time monitoring and alarm capabilities of a room pressure monitor (RPM). RPMs are the safest and most reliable monitoring solution for isolation rooms. A transducer-based pressure sensor–DP transducer makes it more accurate and dependable than a ball pressure indicator and requires zero manual testing.
Some devices also have the ability to monitor temperature and humidity.

Alpha Can Help Keep Hospitals Safe

Alpha has engineered the best devices to protect patients and staff, especially those in isolation rooms. Model 178A can help prevent airborne infections like the coronavirus from spreading.

Model 178A can replace outdated and unreliable technology like a ball pressure indicator or pressure gauge. Using Alpha’s dead-ended variable capacitance pressure sensor, Model 178A allows staff to see at a glance if a room is properly pressurized, even from down the hall.
Unlike the visual-only function of a ball pressure indicator, Model 178A analog output can be directly connected to a BMS to indicate when a room goes into alarm.

Fighting COVID19

Our pressure transducer stop virusfight against COVID-19

Since Novel Coronavirus Outbreak in China ,we all in an effort to support the fight against the novel coronavirus pneumonia epidemic nationwide

In the fight against the virus, negative-pressure ambulances, which allow fresh air in but not out before being properly treated, is much-needed in transporting patients.

For the negative-pressure ambulance,one of the core technology is differential pressure sensor. We alpha instruments Inc. is such company with strong ability on technology . Response to battle with COVID-19,we try our best to support to provide the capacitive pressure sensor to ambulance manufacture JIANGLING MOTORS GROUP CO.,LTD.

The demand of the Ministry of Health for negative pressure ambulances:20 times air change per hour, a negative pressure value between 10Pa to -38Pa, and a filtration separation rate of 99.9%. Therefore,the requirements of barometric pressure sensor are very precise. In order to satisfy the requirement, we provide model No 162with 0.25%FS accuracy. Actually, this accuracy not beyond our highest precision accuracy 0.07%FS.
Additionally, our Alpha low differential pressure transmitter are widely used in clean room, HVAC, Biopharmaceutical, laboratory, building automation, critical environment, etc.

intrinsically safe pressure transducer

Maximum standards – 0.07%FS accuracy

———Significant breakthrough in HVAC industry

September is a harvest season, Through continual technical innovations, we Alpha R&D team make a big breakthrough that our new model 168 intrinsically safe pressure transducer is born with extremely accuracy 0.07%FS defeat the highest 0.25%FS in this industry. pressure range as low as 10pa only. This model use special diaphragm sensors and differential capacitance principle of operation that have the advantage of a perfectly elastic and are better able to handle over pressure and pres-sure spikes.

It is a remarkable benefits technology that performs in low-pressure environments, specifically clean rooms and isolation rooms (hospitals, clinics, etc.) as accuracy, reliability, and stability are so vital. Highly precision is required in these applications.

More important, this improvement will not raise the cost with better function. 10Pa pressure range will expand the application in special condition.

Visit our product information pages to learn more about 168 pressure transmitter which will help you know more about our pressure sensor product .

electronica china 2020

Electronica China show


Venue:Shanghai new international expo center

Booth No:4141


It is the electronics industry’s most important international industry show that product included semiconductor, sensor, connector, power etc, gathering and features a supporting program with forums and conferences such as the electronica Automotive Conference, the Embedded Platforms Conference, the Wireless Congress and the electronica Medical Electronics Conference. A total of 92695 visitors and 1568 exhibitors participated in electronica in 2019.

Welcome to visit Alpha at our Both No 4141, we will keep you update about the confirm show time.