Baumer Solid Front Pressure Gauges: How to Choose the Right Model
A pressure gauge requirement often starts with three details: pressure range, dial size and process connection.
For a normal utility point, that may get you close. For high pressure gas, hazardous process service or an application where failure consequences matter, it is not enough.
This is where a solid front pressure gauge becomes relevant.
Baumer's current Solid Front Pressure Gauges category contains five models: AIF, AIH, AHG, BTF and BTH. AIF and AIH are stainless steel solid front gauges, AHG uses a fibre glass reinforced polypropylene case with stainless steel wetted parts, while BTF and BTH combine a mechanical pressure indication with a 4 to 20 mA transmitter output.
The important question, therefore, is not simply, “Which Baumer solid front gauge is available?” It is, “Which construction actually fits my process?”
What Makes a Solid Front Pressure Gauge Different?
The safety construction is the main reason to consider this category.
The uploaded Baumer AI datasheet describes a baffle wall positioned between the sensing system and the window, together with a pressure relieving back. The intention is increased safety if the pressure element fails.
Baumer's current AIF technical data identifies this as an S3 safety pattern gauge with solid front and pressure relief back according to EN 837 1. The AHG page also identifies an S3 solid front construction.
In practical terms, this is why a solid front gauge should not be treated as just another dial gauge with a stronger case. Its construction is specifically relevant when the application demands a safety pattern design.
Which Baumer Solid Front Gauge Fits Your Application?
AIF and AIH: All Stainless Steel Solid Front Gauges
AIF and AIH are the logical starting point when you need a conventional mechanical pressure gauge with stainless steel wetted parts and solid front safety construction.
The main difference is dial size. AIF is 100 mm and AIH is 150 mm. Both are currently listed with Class 1 accuracy and measuring ranges from 0 to 0.6 bar through 0 to 1600 bar. AIF carries CE and ATEX approvals on the current selector, while AIH is listed with IBR, CE and ATEX.
The uploaded AI datasheet gives more practical detail. It specifies AISI 316L stainless steel for the Bourdon tube and socket, AISI 304 stainless steel for the standard case, movement and blow off disc, IP65 protection, shatterproof safety glass, and dry, fillable or glycerine filled configurations. It also lists an optional accuracy of ±0.5% of full scale for applicable dry versions.
Best for: Process plants where a stainless steel mechanical gauge, wide pressure range and solid front construction are required.
Why these models make sense: AIF gives you the more compact 100 mm format. AIH gives you a larger 150 mm dial when visibility from a greater distance matters.
The current AIF data also lists maximum media temperature up to 300°C for the unfilled version, with lower limits for filled configurations. This is one specification worth checking carefully when the gauge is installed near hot process lines.
AHG: Polypropylene Case with Stainless Steel Measuring System
AHG is different from the AIF and AIH family.
It uses a 4½ inch fibre glass reinforced polypropylene case, while the process connection and Bourdon tube are stainless steel AISI 316L. Baumer currently specifies ±0.5% accuracy according to ASME B40.100, IP65 protection and gauge, compound and vacuum pressure measurement.
The uploaded AH datasheet also describes the solid front construction with a baffle wall and pressure relieving back, AISI 316L wetted parts and dry fillable or glycerine filled configurations.
Best for: Applications where a polypropylene case is preferred while retaining stainless steel wetted components.
Why this model makes sense: AHG is not simply another size of AI. Its case construction and standard ±0.5% accuracy make it a separate selection option.
It is particularly worth comparing with AIF when you need approximately the same dial size but have different requirements for case material or accuracy.
BTF and BTH: Mechanical Gauge Plus 4 to 20 mA Output
This family solves a different problem.
Sometimes the operator needs a pressure reading at the pipe, but the same value also needs to go back to a PLC, PID controller or data logger. Installing a separate gauge and transmitter is not always the preferred arrangement.
BTF and BTH combine local mechanical indication with a pressure transmitter. BTF uses a 100 mm dial, while BTH uses a 150 mm dial. Both are currently listed for gauge, compound and vacuum measurement, with a 2 wire system, 24 VDC supply, DIN electrical connection and 4 to 20 mA output.
The BT datasheet goes further. It specifies a ceramic transmitter diaphragm, AISI 316L stainless steel process connection, 4 to 20 mA output and transmitter accuracy of ≤ ±0.5% FS using BFSL, while the mechanical pressure gauge section is specified at ±1.0% of full scale. It also identifies pharmaceutical, oil, refrigeration, HVAC and compressor industries as applications.
Best for: Applications requiring both local pressure indication and an analog signal for remote monitoring or control.
Why these models make sense: An operator can see pressure locally while the control system receives the 4 to 20 mA signal.
This is also where buyers need to read the specifications carefully. The mechanical gauge accuracy and transmitter accuracy are not the same specification.
Quick Model Selection
| Requirement | Model to Consider |
|---|---|
| 100 mm all stainless steel mechanical solid front gauge | AIF |
| 150 mm all stainless steel mechanical solid front gauge | AIH |
| 4½ inch polypropylene case with SS wetted parts | AHG |
| 100 mm local gauge plus 4 to 20 mA transmitter | BTF |
| 150 mm local gauge plus 4 to 20 mA transmitter | BTH |
Baumer's current category selector confirms these five products and their basic size, range, material and accuracy differences.
How to Select a Solid Front Pressure Gauge Correctly
1. Start With the Actual Operating Pressure
Do not automatically select a gauge whose full scale value is almost equal to the normal process pressure.
The AI and AH datasheets specify normal operating pressure at 75% of scale value. Their overpressure limits then vary according to the selected range.
That makes pressure headroom an important part of selection.
For example, if your process normally operates close to the maximum indicated value, check whether a higher range would provide a more appropriate operating margin.
2. Check the Process Media Against the Wetted Parts
For AIF and AIH, the standard Bourdon tube and process connection use AISI 316L stainless steel. AHG also uses AISI 316L wetted parts.
BTF uses AISI 316L for the process connection and Bourdon tube, while its transmitter section uses a ceramic diaphragm and NBR sealing.
This distinction matters because choosing by case material alone tells you very little about actual process compatibility.
3. Check Process Temperature Before Choosing Dry or Filled
A filled gauge may be attractive when damping is required, but do not assume the process temperature limit remains identical to the dry version.
For example, Baumer's current AIF page specifies media temperatures up to 300°C when unfilled, 100°C when glycerine filled and 200°C with silicone oil.
The AH product page gives a lower maximum process temperature for its unfilled construction, while the BTF and BTH transmitter gauges are listed for media temperatures from minus 25°C to 80°C.
This is one area where copying the pressure range from an existing gauge without reviewing temperature can create the wrong replacement.
4. Decide Whether Local Indication Is Enough
If the reading is only required at the equipment, an AIF, AIH or AHG may be sufficient.
If the same pressure value must also reach a control panel, PLC, PID controller or logger, BTF or BTH deserves closer attention because the BT design provides a 4 to 20 mA transmitter alongside the dial indication.
Do not purchase BTF or BTH without confirming the 24 VDC supply, 2 wire loop and DIN connector arrangement with your panel design.
5. Choose the Dial Size for the Installation, Not the Catalogue
A 150 mm gauge is easier to read from a distance, but it also occupies more space.
AIF and BTF provide 100 mm options. AIH and BTH provide 150 mm options. AHG sits in between as a 4½ inch design.
Check clearance around piping, valves, manifolds and nearby instruments before finalizing the size.
6. Confirm Mounting and Process Connection
The AI datasheet provides several mounting arrangements, including direct bottom entry and additional mounting options. Standard connection options include ½ inch BSP male and ½ inch NPT male, with M20 × 1.5 and other connections also listed.
The AH datasheet includes wall or surface mounting, direct lower back entry and lower back entry with front flange. One particularly important detail is that the direct lower back entry configuration is identified as never fillable.
That is the type of small ordering detail that can become a large site problem if it is missed.
Common Selection Mistakes
| Common Mistake | Better Approach |
|---|---|
| Choosing only by pressure range | Check operating pressure, overpressure, temperature and media |
| Assuming every solid front model has the same accuracy | Compare Class 1 AI models, ±0.5% AHG and transmitter specifications separately |
| Selecting a filled gauge without checking temperature limits | Confirm fill liquid and allowable process temperature |
| Ordering BTF or BTH only because it has a transmitter | Confirm 24 VDC, 2 wire, 4 to 20 mA and PLC or controller input |
| Looking only at case material | Check actual wetted parts and sealing materials |
| Ordering the same connection as the old gauge without checking mounting | Verify connection thread, entry position and available clearance |
| Treating BTF transmitter accuracy as mechanical gauge accuracy | Review both specifications separately |
One Source Detail Worth Confirming Before Ordering
There are a few differences between the uploaded April 2025 datasheets and Baumer's current web data.
For example, the AI datasheet lists a standard ambient temperature of minus 20°C to +65°C, while the current AIF web page lists minus 25°C to +65°C.
The AH PDF shows pressure ranges beginning at 0/0.6 bar, while the current AHG web page displays its minimum range as 0 to 0.6 mbar.
Because these sources do not fully agree, confirm the latest model datasheet and ordering code before final purchase, especially for the lowest pressure range and temperature limits.
Quick Selection Checklist
Before sending an inquiry for a Baumer solid front pressure gauge, confirm:
- Gauge, vacuum or compound pressure requirement
- Normal operating pressure
- Maximum expected pressure
- Process media
- Process temperature
- Required accuracy
- 100 mm, 150 mm or 4½ inch dial
- Dry, fillable or liquid filled construction
- Bottom, back or other mounting requirement
- BSP, NPT, M20 or other process connection
- Required material of wetted parts
- IP and approval requirements
- Whether only local indication is needed
- Whether 4 to 20 mA output is required
- Calibration or material certificates required
Why Buy Baumer Solid Front Pressure Gauges from Radical TechMart?
A pressure gauge inquiry should not stop at “0 to 100 bar, ½ inch connection.”
The correct selection also depends on media, operating pressure, temperature, mounting, dial size, material, accuracy, fill requirement and whether the pressure value must stay local or be transmitted to a control system.
At Radical TechMart, the focus is to help industrial buyers compare these application details before finalizing the instrument.
Whether the requirement is an AIF or AIH mechanical solid front gauge, an AHG polypropylene case gauge, or a BTF or BTH gauge with 4 to 20 mA transmission, the selection should start with the process conditions.
Final Thoughts
The biggest advantage of the Baumer solid front pressure gauge range is not that it gives you five model numbers to choose from. It gives you different constructions for different types of pressure measurement jobs.
Choose AIF or AIH when you need an all stainless steel mechanical safety pattern gauge. Consider AHG when its polypropylene case construction and ±0.5% accuracy fit the application. Look at BTF or BTH when the requirement includes both a local dial and a 4 to 20 mA signal.
In industrial pressure measurement, the correct gauge is selected by understanding what happens at the process connection, not simply by matching the dial range printed on the old instrument.
FAQs
1. What is a Baumer solid front pressure gauge?
It is a safety pattern pressure gauge with a solid barrier between the sensing system and viewing side, together with pressure relief construction. Baumer identifies AIF and AHG as S3 safety pattern gauges.
2. What is the difference between AIF and AIH?
The main model distinction is nominal size. AIF is 100 mm and AIH is 150 mm. Both are listed as stainless steel solid front gauges with Class 1 accuracy and measuring ranges up to 1600 bar.
3. What is the difference between AIF and AHG?
AIF uses a stainless steel case and has Class 1 accuracy. AHG uses a fibre glass reinforced polypropylene case and is listed at ±0.5% accuracy according to ASME B40.100. Both use stainless steel wetted parts.
4. Which Baumer pressure gauge provides 4 to 20 mA output?
BTF and BTH provide local pressure indication together with a 2 wire 4 to 20 mA transmitter operating from 24 VDC. BTF is 100 mm and BTH is 150 mm.
5. Can Baumer solid front gauges measure vacuum and compound pressure?
Yes. The AI, AH and BT families include gauge, compound and vacuum pressure options, subject to the selected model and range.
6. Can I use a glycerine filled solid front gauge?
Selected AI and AH configurations are available as fillable or glycerine filled versions. Temperature limits and mounting restrictions should be checked before ordering.
7. Which model should I select for PLC pressure monitoring?
If both local indication and a standard analog pressure signal are required, BTF or BTH are the relevant models in this category because they provide 4 to 20 mA output.
