If you choose the wrong pressure reference, a sensor can give readings that look correct but mislead your control system, test data or commissioning decisions. We use gauge, absolute and differential pressure to describe three different relationships: pressure compared with local atmosphere, pressure compared with a vacuum, and pressure compared between two points.
At Diversified Technologies, we want you to understand that distinction before you specify a transmitter, calibrate an instrument or compare values such as PSIG, PSIA and PSID. The practical difference affects vacuum measurement, sealed systems, tank level, filter monitoring, flow measurement and any application where changing atmospheric pressure matters. In this guide, we explain the concepts in plain engineering terms, show common conversions, and highlight the mistakes that can lead to mismatched sensors or incorrect assumptions. If you are selecting or integrating pressure sensors, we help you approach the decision from the measurement point backwards, not from the part number forwards.
- Choose gauge pressure for readings relative to local atmosphere, absolute pressure for vacuum-referenced readings, and differential pressure for two-point comparisons.
- Gauge pressure suits tanks, pneumatic lines, hydraulic circuits, pump discharge checks and HVAC measurements where local atmosphere is the reference.
- Absolute pressure is needed when atmospheric changes would skew readings, including vacuum packaging, condenser monitoring, altitude testing and gas-law calculations.
- Differential pressure requires correct high and low port selection and separate checks for differential range, working pressure and overload limits.
What is gauge pressure?
Gauge pressure is pressure measured relative to local atmospheric pressure. A vented gauge reads zero when open to air because both the process port and the reference side see the same ambient air. In practical terms, this is the number you care about when a system’s push or pull relative to today’s atmosphere is what matters.
The reference point is the air around the instrument, not a perfect vacuum. If the process is higher than the surrounding atmosphere, the displayed value is positive; if it’s lower, the value is negative, which is why vacuum readings are often shown as a minus figure. That said, many product catalogues and datasheets call the same concept relative pressure, so you may see “relative”, “vented”, or “PSIG” used for broadly similar measurement intent.
According to WIKA’s manufacturer guidance on pressure types, relative pressure is obtained by subtracting ambient atmospheric pressure from absolute pressure; it expresses the relationship as pe = pabs − pamb.
A common sensor design puts the process media on one side of the sensing element and leaves the other side vented, or otherwise referenced, to atmosphere. That design makes the reading track local weather and altitude changes automatically. At sea level, standard atmosphere is 101.325 kPa absolute, but local atmospheric pressure moves with elevation and conditions, so two identical systems can show different relative readings if they’re installed in different places.
- The reference is local air: The instrument reports pressure compared with the ambient air around the device, not compared with vacuum.
- The reading can be positive or negative: A pressurised vessel may show a positive value, while a suction line or vacuum chamber may show a value below zero.
- The vent path matters: A blocked vent can make a relative transmitter behave incorrectly because it no longer sees the same atmosphere as the installation area.
- The datasheet wording may vary: Review whether the range is labelled relative, vented, sealed, absolute, PSIG, or another reference before comparing models.
For selection work, this reference type is a good fit for tanks open to atmosphere, pneumatic lines, hydraulic circuits, pump discharge checks, and many HVAC measurements. It’s usually easier for operators to interpret than an absolute vacuum sensor, because zero corresponds to the air around them. It’s also simpler than a differential device when you don’t need a high-side and low-side connection.
If you’re reviewing an IP67 pressure transmitter, a HART pressure transmitter, or a BD Sensors datasheet, check the reference type before comparing accuracy, turndown ratio, process connection and material compatibility. Stainless steel, Hastelloy, elastomers and the mechanical interface affect whether the sensor suits the media and installation, but the pressure reference determines what the number actually means. Calibration records should also state the reference used, because a relative reading is only meaningful when its atmospheric reference is understood.
The strongest rule is simple: this measurement doesn’t tell you total pressure from vacuum; it tells you how far the process sits above or below the air surrounding the instrument.
What is absolute pressure?
Absolute pressure is pressure measured from a perfect vacuum, where zero means no pressure remains. You need this reference when changes in atmospheric pressure would skew the reading, such as in vacuum packaging, condenser monitoring, altitude testing or gas-law calculations. At sea level, normal barometric pressure is about 14.7 psia, so a vessel reading 0 psig isn’t empty; it’s roughly 14.7 psia before local weather changes are considered.
The main difference from gauge or differential measurement is the sensor reference. Instead of venting one side to atmosphere, the transmitter uses a sealed evacuated chamber as its fixed baseline. That keeps the reading stable for low-pressure and vacuum duties, but it also means you must specify the scale correctly: a 4-20 mA pressure transmitter ranged in psia won’t match a gauge transmitter ranged in psig without conversion.
Tell us about the process, the media and what the control system needs to see, and our engineers will confirm whether gauge, absolute or differential is the right reference before you order.
What is differential pressure?
Differential pressure compares two points in the same system, rather than measuring pressure against atmosphere or vacuum. In practice, it’s the difference between the pressures at a high port and a low port, and it helps indicate flow, filter loading, tank level or fan performance.
- Identify the two reference points before choosing an instrument. In a filter skid, the upstream side connects to the high port and the downstream side connects to the low port, so rising differential pressure shows blockage rather than rising line pressure.
- Decide whether you need a switch or a transmitter. A differential pressure switch changes state at a set point, which suits alarm duties, while a transmitter gives a continuous signal for PLC control, trend logging and fan-speed control.
- Check the measuring range against the real process condition. A transmitter selected for 0 to 100 mbar can suit HVAC duct monitoring, but it can be damaged if a pump start-up applies several bar to one side without equalisation valves.
- Check the line pressure rating as well as the differential range. High static pressure can exist on both ports when the measured difference is small, so our selection work separates working pressure from differential span and checks overload limits in the datasheet.
- Match the wetted materials to the medium. Stainless steel is common for water, oils and clean gases, while Hastelloy may be the safer choice for chloride-bearing liquids or chemical vapours that would attack standard diaphragms.
- Specify the process connection and installation layout. The mechanical interface must match the tappings and pressure class, but differential pressure transmitter mounting matters just as much because impulse lines must drain, vent or stay filled according to the service.
- For level measurement, use differential pressure only when density is known. The level measurement DP equation is ΔP = ρgh, where rho is density, g is gravitational acceleration and h is liquid height, so temperature changes can shift the indicated level.
- Ask for calibration evidence for the range you intend to use. IEC 61298-2 is the recognised framework many instrumentation teams use when reviewing transmitter accuracy tests. If you’re using a BD Sensors datasheet, review output, accuracy class and process compatibility before comparing sensor types.
The step people most often get wrong is treating differential range as the whole pressure duty. A low-span instrument can sit on a high-pressure line, so we check both ports and both isolation states carefully.
What are PSIG, PSIA, and PSID and how are they different?
The three psi suffixes matter because PSIG, PSIA, and PSID tell you what the pressure is being measured against: PSIG is pounds per square inch gauge against ambient atmosphere, PSIA is pounds per square inch absolute against a perfect vacuum, and PSID is pounds per square inch differential against another pressure point in the system.
The suffix is PSIG: it’s measured against ambient atmosphere. Common on tyre pressure labels. The suffix is PSIA: it’s measured against a perfect vacuum. Used in barometer and vacuum calculations. The suffix is PSID: it’s measured against another system pressure point. Used for filter monitors across inlet and outlet.
If a datasheet says psi without G, A, or D, we ask for clarification before choosing hardware. That prevents fitting the wrong transmitter on site.
Quick comparison: gauge vs absolute vs differential (at a glance)
Start with the reference point; it usually narrows the choice quickly. If a tank, pipe or hydraulic line needs to be compared with ambient air, choose an atmosphere-referenced transmitter. Use a vacuum-referenced device when barometric change would distort the result. Use a two-port instrument when you need the difference between two points. In simple terms, reference selection is the factor that most often decides the correct sensor.
| Decision factor | Atmosphere reference | Vacuum reference | Two-point reference |
|---|---|---|---|
| What it measures | It measures process pressure compared with surrounding atmospheric pressure. | It measures process pressure compared with a sealed internal vacuum chamber. | It measures the pressure difference between a high-side port and a low-side port. |
| Best fit | Best for hydraulics, compressed air, pump discharge and vented storage vessels in most installations. | A better fit for vacuum systems, altitude-sensitive testing, weather-related compensation and low-pressure scientific measurement. | Often chosen for filter monitoring, HVAC air balancing, tank level and flow across an orifice plate. |
| Typical output | It commonly reports values such as bar, psi or millibar above local atmosphere, often through 4–20 mA or 0–10 V signals. | It commonly reports psia, bara or mbar abs where zero means a perfect vacuum, not ambient air. | It commonly reports psid, mbar d or Pa d, and a transmitter may linearise the signal for flow or level. |
| Main advantage | It gives intuitive readings for operators because zero normally means the line or vessel is vented to air. | It stays stable when atmospheric pressure changes, which can be important because sea-level air pressure is about 101.3 kPa. | It directly measures the variable that matters in many processes, without subtracting two separate sensor readings later. |
| Main limitation | It can shift with weather or altitude because the reference is ambient air. | It can confuse users if they expect a vented reading, especially when converting vacuum values. | It needs careful impulse-line routing, correct high/low port connection and suitable mounting to avoid trapped gas or condensate errors. |
| Selection checks | Check pressure range, overload rating, process connection such as 1/4″ NPT or G1/2, and pressure sensor material compatibility. | Check whether an absolute vacuum sensor is required, then review the BD Sensors datasheet for range, accuracy class and wetted materials. | Decide between a differential pressure switch vs transmitter: a switch suits an alarm point, while a transmitter suits continuous control. |
| Installation notes | Use an IP67 pressure transmitter where washdown, outdoor exposure or condensation could affect the electrical connection. | Protect the sensing diaphragm from harsh media by specifying stainless steel, Hastelloy or an isolation seal where needed. | For liquids, mount below the tapping points where practical; for gases, mount above them to reduce liquid carry-over into impulse lines. |
| Documentation | Label documentation so atmosphere-referenced readings are not mistaken for absolute values. | According to ISO/IEC 17025 practice, traceability and stated uncertainty matter as much as the displayed number. | For tank level, the level measurement DP equation is commonly expressed as height equals differential pressure divided by fluid density and gravity. |
The deciding factor is rarely the display unit; it’s the physical reference behind the number. A sensor that reads against atmosphere reports a relative value, a sensor that reads against vacuum reports a true value from zero pressure, and a two-port device reports the difference between two process points. That distinction prevents expensive mistakes: a vacuum oven, for example, may need absolute measurement, while a clean-room filter bank normally needs a low-range two-port transmitter in pascals. For harsh fluids, we also review wetted parts and process connections before accuracy, because stainless steel or Hastelloy compatibility can matter more than a tighter percentage specification.
Sealed gauge vs vented gauge vs absolute: what's the real difference?
Your application needs the reference point before it needs the range. Start with a vented gauge pressure sensor if the process needs to follow local atmosphere, use a sealed reference when moisture or contamination could block a vent, and move to a vacuum-referenced instrument when barometric pressure must not influence the reading.
| Decision factor | Open-reference option | Sealed-reference option | Vacuum-reference option |
|---|---|---|---|
| Start by pinning down the reference point. | The sensor compares process pressure with surrounding air through a vent path. | The sensor compares process pressure with a factory-sealed chamber, often near one atmosphere. | The sensor compares process pressure with a sealed vacuum chamber. |
| Best fit comes down to environment and measurement purpose. | It suits tanks, hydraulics, compressors and general plant service where ambient air is clean enough. | It suits washdown, subsea, outdoor and high-pressure duties where a vent can fail. | It suits vacuum systems, barometric pressure measurement, altimetry and gas laws work. |
| The main advantage is different for each design. | It removes normal weather changes from the indicated process value. | It protects the reference side from condensation, dust and blocked breather tubes. | It gives a stable reading that can be compared across sites and altitudes. |
| Check the main limitation before you specify it. | The vent path can admit moisture unless cable routing and sealing are controlled. | The reading includes a small offset as barometric pressure moves around the sealed reference. | The reading must be converted if operators expect a value relative to local atmosphere. |
| The output can use common industrial formats. | It can be supplied as a 4-20 mA pressure transmitter or a HART pressure transmitter. | It can use the same electrical outputs while adding better environmental robustness. | It can report PSIA, bar or kPa referenced to zero pressure. |
| The mechanical interface should match the process. | It commonly uses threaded or flush diaphragm connections. | It commonly uses stainless steel or Hastelloy wetted parts for harsh media. | It commonly uses threaded or flange connections where leak integrity is critical. |
The deciding factor is usually barometric pressure. Standard atmosphere is 101.325 kPa, or 14.696 psi, but real ambient pressure shifts with weather and elevation. A vented design cancels that shift; a sealed design tolerates it; a vacuum-referenced design measures it. For high turndown ratio pressure sensor applications, we’ll also check whether a 0.5 psi atmospheric swing is trivial or large enough to distort control decisions. That review prevents the common mistake of specifying a rugged instrument that is referenced to the wrong zero.
Can gauge pressure be negative and what does negative gauge pressure mean?
Gauge pressure can be negative when the measured pressure is below local atmospheric pressure. In everyday plant language, that’s a vacuum or suction condition relative to ambient air. A negative PSIG value doesn’t mean negative absolute pressure; it means the process is below the atmospheric reference used by the instrument. The real pressure remains above zero unless a perfect vacuum is reached.
The important limit is physical, not just numerical. According to NIST, one standard atmosphere is 101.325 kPa, or 14.696 psi, at the defined standard condition. Local air pressure varies with elevation and weather, so a below-atmosphere reading can approach the negative of the local barometric reference rather than one universal number. The lowest physically possible value is zero absolute pressure, sometimes described as perfect vacuum. For practical pressure measurement, verify the reference condition on the instrument range, datasheet and pressure calibration certificate.
- A vacuum pump inlet is pulling gas out of a chamber: The process pressure is lower than the surrounding air, so the indicator moves below zero on a PSIG scale. Review the manufacturer range statement and confirm the sensor is rated for vacuum exposure.
- A pump suction line is operating below ambient pressure: The line may still contain liquid, but its static pressure is below the local atmospheric reference. Check wetted materials, cavitation risk and whether the diaphragm tolerates reverse loading.
- An engine intake manifold is under suction during part-load operation: The manifold is not at negative real pressure; it is simply below the air pressure outside the engine. Use a range that covers both vacuum and positive boost if the application can see both states.
- A sealed vessel is held under partial vacuum: The vessel pressure is between perfect vacuum and ambient air, not below the physical zero point. Confirm the port, seal material and enclosure suit the gas, vapour or cleaning medium present.
Instrument selection is where mistakes become expensive. A vented pressure sensor compares the process with ambient air through a reference path, so it can show suction if the specified span includes it. A sealed reference transmitter compares against a trapped reference pressure, which is useful in some harsh or wet environments but not identical to an evacuated reference. An absolute sensor uses a vacuum reference chamber, so it won’t display negative PSIA. In comparisons like this, the minus sign is reference information first and a mechanical loading case second.
For applications that may see negative readings, specify vacuum-rated or compound service, not a positive-only range chosen by habit. Worth noting: a BD Sensors datasheet, or any equivalent manufacturer document, should state whether the measurement span covers below-atmosphere operation and whether the device can withstand full vacuum at the process connection. This matters for the selected port style and mounting arrangement, as well as for stainless steel or Hastelloy wetted parts in corrosive media. For a differential transmitter, a negative value can also occur when the low side exceeds the high side; correct impulse-line routing and differential pressure transmitter mounting help prevent a sign error from being mistaken for a real process vacuum.
The basic rule is simple: a negative PSIG reading is a below-atmosphere condition, not impossible physics. Treat it as a valid measurement only when the reference, range, calibration record and mechanical rating all support operation below ambient air.
Send us the range, media and installation detail and we’ll check the reference type, overload rating and wetted materials against the duty before anything is ordered.
How to choose the right pressure sensor: a step-by-step checklist
A commissioning engineer is standing beside a vacuum pump and one spare process port. First, pin down the reference, because gauge, absolute and differential sensors don’t measure the same thing.
First, decide what the sensor must compare against. Choose vented gauge for local atmosphere, sealed gauge for a fixed reference, absolute for vacuum-referenced pressure, or differential for high and low process tappings. Use differential pressure switches for alarms and transmitters for trends. Next, set the range, then check proof pressure. A turndown ratio pressure sensor can cover changing conditions, but it won’t save an underspecified diaphragm from pressure spikes. Then, match the signal to your controls. We recommend 4-20 mA with HART pressure transmitter diagnostics for long cable runs; 0-10 V is usually better kept to short, low-noise panels.
After that, check wetted materials against the media. Stainless steel suits many hydraulic oils, while Hastelloy may be safer for corrosive chemicals. After that, choose the process connection and enclosure. Common options include 1/4″ NPT, G1/2 and flange mounts, and an IP67 pressure transmitter is rated under IEC 60529 for dust and temporary immersion. Finally, specify calibration evidence. A pressure calibration certificate should show range, reference standard, uncertainty and test points.
In practice, most errors come from choosing range before reference.
When to use differential pressure for level and flow
Differential pressure is the right choice when the useful value is the pressure difference between two points, not the pressure at one port. Worth noting: for tank level, that difference represents liquid head; for flow, it represents the energy lost across an orifice plate or Venturi.
- Use differential measurement where level depends on liquid height rather than vessel pressure. In a closed tank, connect the high side to the lower tapping and reference the low side to the vapour space, so changing blanket pressure cancels out.
- Work out the span from hydrostatic head before choosing the transmitter range. Using ΔP = ρgh, a 1 metre water column at 20 °C is approximately 9.79 kPa, while denser fluids scale with specific gravity. Keep the operating span comfortably inside the turndown ratio pressure sensor stated on the relevant BD Sensors datasheet.
- Choose wet-leg, dry-leg or capillary seals to suit the vapour and ambient conditions. A wet leg suits condensing services such as steam, but outdoor frost risk can make a remote diaphragm seal safer. Material compatibility matters: stainless steel is common, while Hastelloy may be specified for more aggressive media.
- Differential flow measurement makes sense when the primary element creates a repeatable restriction. Flow is proportional to the square root of differential pressure, so doubling DP doesn’t double flow. According to ISO 5167, orifice plate systems depend on defined geometry and pressure-tapping arrangements.
- Decide whether a differential pressure switch or a transmitter is the better fit. Pick a switch for a discrete alarm, such as filter blockage or pump proof. Specify a transmitter when the control system needs a continuous signal, such as 4-20 mA, voltage output or a HART pressure transmitter for ranging and diagnostics.
- Plan the impulse lines before the instrument is ordered. Mount the differential pair with the high and low ports correctly identified, slope lines so gas or liquid pockets don’t bias the reading, and keep both legs at comparable temperature. Confirm the selected interface matches the process tappings and pressure class.
- Check enclosure and documentation requirements against the plant environment. An IP67 pressure transmitter is often appropriate where washdown or outdoor spray is credible, but electrical approvals, cable entry and earthing still need review. Ask for a pressure calibration certificate when traceability is part of your quality system.
Installation geometry is the step people most underestimate. A correctly ranged transmitter can still give errors if impulse-line routing traps condensate, vents gas unevenly or reverses the high and low references.
Calculations and conversion examples (gauge to absolute, DP to level)
1.01325 bar is standard atmospheric pressure, so a skid-mounted water system can convert its pump gauge reading by adding the barometric reference. For example, if the gauge shows 2.0 barg at standard atmosphere, we calculate 2.0 + 1.01325 = 3.01325 bara. At altitude, use the measured barometric pressure instead, because an absolute vacuum sensor references a sealed vacuum chamber, not room air.
On the same skid, you might also have a differential transmitter for tank level, with the low side vented to atmosphere and the high side connected to a bottom tapping. A 20 kPa DP equals 20,000 Pa. Put that into h = ΔP ÷ (ρ × g), with water at 1,000 kg/m³ and gravity at 9.80665 m/s², and we get 2.04 m. For chemicals, check pressure sensor material compatibility before trusting the number. Calibration documentation should confirm units and reference type.
What mistakes happen when confusing gauge pressure with absolute pressure?
Mixing up gauge pressure and absolute pressure creates offset errors because the two readings use different zero points: atmosphere for one and vacuum for the other. The common mistake is entering PSIG into a calculation that requires PSIA, especially in gas-law, compression, vacuum and mass-flow work. At standard sea-level atmosphere, that error is about 14.7 psi.
One common shop-floor example is a packaging line with a pneumatic compression stage upstream of a vacuum chamber. The operator’s HMI shows 30 PSIG, so a process calculation is completed using “30 psi” as the inlet pressure. If the compressor sizing, density estimate or mass-flow equation expects an absolute value, the input should be about 44.7 PSIA, not 30. The result isn’t a subtle rounding difference; the calculation has ignored the atmospheric-pressure offset and can understate the available gas pressure by roughly one third.
The same confusion feels different during vacuum testing. A chamber reading of -5 PSIG isn’t “minus five pounds below vacuum”; it’s about 9.7 PSIA when local atmospheric pressure is close to 14.7 psi. If you treat the negative display as an absolute line item, the calculation becomes physically impossible because pressure can’t fall below a perfect vacuum. That’s why engineering notes, alarm schedules and pressure calibration certificate data need to state the reference as clearly as the number.
- A calculation uses bare “psi” without a reference: The engineer may enter a vented reading into a gas-law, compression, vacuum or mass-flow calculation that requires a vacuum-referenced value. Every calculation sheet should label the input as PSIG, PSIA or PSID before any formula is approved.
- A sensor is specified with the wrong reference: An absolute sensor may show about 14.7 psi in open air when the operator expects zero, or an atmosphere-referenced gauge transmitter may not suit a sealed reference requirement. Check the datasheet for whether the device is vented, sealed or vacuum-referenced before purchasing.
- An apparent pressure discrepancy appears during calibration: The transmitter, calibrator and HMI may all be correct, while the offset is simply atmospheric pressure being included in one reading and excluded in another. The pressure calibration certificate should record the applied reference condition, not only the displayed range.
- A shared document states only “psi”: Purchasing, calibration and alarm-setpoint errors can follow because each team may assume a different zero point. Datasheets, HMI screens, procedures and test reports should use explicit PSIG, PSIA or PSID labels throughout.
According to NIST Special Publication 811, technical quantity values must be expressed unambiguously through the number, unit and surrounding information. In pressure measurement standards and manufacturer literature, that means the reference is part of the measurand, not a note to add later. The key distinction: a BD Sensors datasheet, for example, treats range and pressure type as separate selection details; that distinction matters when comparing sealed gauge vs absolute pressure or reviewing a sealed gauge pressure transmitter for a closed system.
The practical rule is simple: if two readings differ by roughly atmospheric pressure, do not assume a faulty transmitter first. Start by reviewing the reference, the sensor type and the label on the display. Clear units are the cheapest safeguard against buying the wrong instrument, calibrating against the wrong target or setting an alarm at the wrong physical pressure.
Contact Diversified Technologies for sensor selection and integration
The same reference choice needs to carry into the transmitter specification, not sit as a note in the datasheet. From there, we help you turn gauge, absolute or differential pressure choices into a buildable sensor package. Range, media compatibility and output signal affect whether the right device is an atmosphere-referenced transmitter, an absolute transmitter or a differential pair.
A 4-20 mA pressure transmitter suits long analogue cable runs, while a HART pressure transmitter adds digital configuration and loop diagnostics. The plant connection and mounting style need to suit the installation, not just the pressure range. Harsh media may push wetted parts from stainless steel to Hastelloy. Differential duties need high and low ports, sensible impulse line routing and a turndown ratio matched to manometer, tank level or orifice plate differential pressure flow.
Speak with a Diversified Technologies engineer on 585-461-2110 for help with gauge, absolute and differential sensor selection, ranging, materials and calibration documentation.
Frequently Asked Questions
Altitude and weather change local atmospheric pressure, so gauge readings and absolute readings can diverge by a changing offset even when the process pressure is unchanged. At higher elevation, atmospheric pressure is lower, which changes the relationship between gauge and absolute values. For critical work, use the measured barometric pressure at the instrument location rather than assuming a standard atmosphere.
A compound-range gauge transmitter can measure pressures below and above local atmosphere, but it still reports values relative to atmospheric pressure rather than perfect vacuum. If the process must be controlled by true vacuum level, an absolute transmitter is usually the clearer choice. The key is to match the sensor reference to the control variable, not just the numeric span.
Pressure units describe magnitude, not reference point, so psi, bar, and kPa are incomplete unless the reading is identified as gauge, absolute, or differential. A value written only as “100 psi” can be ambiguous in engineering, calibration, and purchasing documents. Add suffixes or wording such as psig, psia, kPa absolute, or bar differential wherever the reference matters.
A pressure instrument tag or drawing should state the pressure range, units, reference type, process connection, media conditions, and any required output signal or hazardous-area rating. The reference type is especially important because the same numeric range can mean different things for gauge and absolute devices. Clear labels also help technicians verify replacements during maintenance.
Proof pressure is the maximum pressure a sensor can withstand without permanent specification change, while burst pressure is the level where mechanical failure may occur. Neither value is the same as the normal operating range. A sensor should be selected so routine pressure, expected spikes, and abnormal events remain within the appropriate datasheet limits.