Install pressure taps where they answer a defined question. Use suitable inlet and discharge taps to assess blower pressure rise, taps on both sides of a filter to monitor differential pressure, a main-header tap to track system demand, and branch taps when several air knives or process zones must be compared.
Place taps in representative straight sections where possible, away from elbows, valves, reducers, branch entries and direct high-velocity jets. A gauge beside the blower may be convenient, but it cannot show pressure at the process after pipe losses. Record the exact location, pressure type, reference, units and operating condition so future readings remain comparable.
Begin with the Measurement Purpose
There is no single “best” gauge position for an entire air system. The correct point depends on the fault or operating condition that needs to be detected.
For example:
- a discharge gauge can show changes near the blower;
- an inlet gauge can reveal suction-side restriction;
- two filter taps can track filter loading;
- a remote header gauge can expose downstream pipe loss;
- branch gauges can help diagnose uneven air knives;
- a terminal-device tap can support process commissioning.
Before adding hardware, write the question beside each proposed point on the drawing. If a reading will not lead to a maintenance or control decision, the port may provide little value.
Location 1: Blower Inlet
An inlet static-pressure tap helps identify resistance upstream of the blower. It can reveal a loaded filter, restrictive silencer, undersized inlet pipe or blocked intake.
Inlet gauge pressure is often negative relative to the surrounding atmosphere. Use an instrument that displays the required negative range and cannot be damaged by the expected vacuum.
Locate the tap in a representative section between the final upstream component and the blower inlet, following the blower maker’s guidance. Avoid placing it directly at an elbow, abrupt reducer or bell-mouth disturbance. If there is too little straight pipe for an ideal point, document the limitation.
An inlet reading alone does not show filter differential pressure unless the upstream side of the filter is effectively and intentionally referenced to atmosphere. Dedicated taps on both sides provide a clearer measurement.
Location 2: Blower Discharge
A discharge tap tracks static pressure leaving the blower and can support alarm or trend monitoring. It is useful during commissioning, but should not be drilled into an unsuitable part of the blower casing or connection without manufacturer approval.
Place the tap in a straight section downstream of the discharge transition where practical. The immediate outlet may contain swirl and a nonuniform velocity profile. A local reading there can differ from the average pressure farther downstream.
Discharge gauge pressure is not necessarily the blower’s complete pressure rise. If the inlet operates below atmospheric pressure, the inlet condition also matters. In addition, the pressure definition used for a factory curve may include total-pressure terms that a simple wall tap does not measure.
For curve comparison, follow the manufacturer’s specified inlet and discharge reference planes and pressure basis.
Location 3: Across the Inlet Filter
Filter monitoring requires two points: one upstream and one downstream. Connect these to a differential-pressure gauge or transmitter, or take matched readings with a suitable instrument.
The difference indicates how much pressure the filter consumes at the current airflow. This is more informative than inspecting appearance alone. A filter can look dirty yet remain within its permitted loss, while fine contamination may create restriction that is not visually obvious.
Pressure drop varies with airflow. Compare trends at the same blower speed and outlet configuration where possible. A higher reading caused by increased flow is not necessarily evidence that the filter suddenly failed.
Set maintenance limits according to the filter, blower and final equipment manual. A nominal time interval can be used as an inspection starting point, but site dust conditions and measured trend should govern the final schedule.
Location 4: Main Distribution Header
A header gauge shows the pressure available before air divides into process branches. Comparing discharge and header readings can help identify loss through the connecting main pipe, common fittings or accessories.
Select a point after the main flow has stabilized and before the first branch if the layout permits. A tap directly opposite a branch entry or at the end of a high-velocity feed may see local effects rather than representative static pressure.
For equipment with different production recipes, header pressure is useful only when the active outlets and blower speed are recorded. Closing two air knives can raise pressure without indicating improved system health.
Location 5: Individual Air-Knife or Process Branches
Branch taps help compare parallel routes and diagnose uneven output. Install them at comparable locations relative to each terminal device. If one tap is beside the manifold and another is beside the knife after several metres of hose, their values cannot be compared directly.
A branch pressure reading should be assessed with outlet velocity or process performance. High pressure upstream of a narrow, blocked or incorrectly set slot may coexist with inadequate airflow.
On a multi-knife system, useful information may include:
- header pressure;
- pressure near each knife inlet;
- valve position;
- knife gap and effective length;
- outlet-velocity profile;
- product drying result.
This combination separates a distribution problem from a total blower-capacity problem.
Location 6: Across Suspected Restrictions
Permanent or temporary taps on both sides of a component allow its pressure loss to be measured directly. Candidates include silencers, heat exchangers, valves, long hose sections and treatment devices.
Install such points only where the expected diagnostic value justifies the added fittings. Every port must remain sealed, mechanically sound and accessible. Unused or poorly maintained taps can become leaks.
When comparing component differential pressure, hold flow reasonably constant. Pressure loss changes with airflow, so readings from different operating states should not be treated as a simple condition trend.
Where a Pressure Tap Should Not Be Placed
Avoid locations immediately beside:
- an elbow or tee;
- a reducer or sudden enlargement;
- a control or isolation valve;
- a manifold branch entry;
- a flexible-hose corrugation;
- a blower outlet with strong swirl;
- an air-knife inlet jet;
- a known leakage point.
Also avoid a tap that protrudes into the flow when static pressure is intended. The opening should generally be flush with the internal wall, clean and free of burrs. Incorrect orientation can introduce a velocity-pressure component.
Industrial equipment often lacks ideal straight lengths. In that case, choose the most repeatable practical point, consider several circumferential taps or a purpose-designed measuring section, and state the limitation in the report.
Gauge Installation Details That Affect Reliability
Instrument range
Choose a range close enough to the expected value for useful resolution, while allowing safe overpressure. A gauge spanning far beyond normal pressure may show only coarse changes.
Tubing
Use compatible tubing, keep runs protected and avoid kinks. Condensation, dust or process liquid can block a small line. Arrange maintenance access and drainage where needed.
Isolation and protection
Provide suitable isolation where the gauge requires service, but prevent a closed gauge valve from being mistaken for a zero-pressure system. Protect the instrument from vibration, heat and accidental impact.
Zero and calibration
Zero the instrument as specified before testing. Follow a calibration schedule appropriate to the decisions based on the reading. A digital display does not guarantee accuracy.
Units and labels
Label the port, pressure type and units. kPa, mbar, Pa and mmH₂O are easily confused. Mark whether a reading is positive discharge pressure, negative inlet pressure or differential pressure.
A Practical Measurement Map
For a blower feeding several air knives, a useful arrangement may be:
- one tap upstream of the inlet filter;
- one tap between the filter and blower;
- one discharge tap at the approved reference section;
- one main-header tap before branching;
- one comparable tap near each critical knife;
- optional taps around a high-loss component.
Not every system needs every point. A compact machine may use portable instruments connected to capped ports, while a continuous line may justify fixed transmitters and alarms.
Create a pressure-point diagram with unique tags. Photographs and measured distances from fittings make future testing reproducible.
How to Use the Readings Together
Pressure differences are often more diagnostic than isolated values.
- Rising filter differential with falling airflow suggests filter loading.
- Normal discharge pressure but low remote-header pressure suggests added loss between those points.
- Stable header pressure with one weak knife suggests a branch or terminal problem.
- Higher overall pressure with lower total airflow can indicate a system restriction.
- Lower pressure and poor performance may indicate leakage, lower speed or reduced blower output.
These are diagnostic patterns, not automatic conclusions. Confirm them with airflow, electrical data, physical inspection and process results.
Applying Gauge Data to Towwind Blower Selection
Tag each gauge location and define the pressure type and reference. For replacement selection, compare the measured airflow-pressure point with the exact model’s released curve; separate catalogue endpoints do not describe the installed duty.
Send the supplier tagged pressure locations, airflow or outlet configuration, speed, pipe layout, filter condition, electrical readings, duty cycle and ambient conditions. Confirm usable control limits and test procedures for the delivered model.
Confirm controls, cooling clearance and the final connection drawing before fabrication. Gauge data improves selection only when its location and basis are documented.
Pressure Monitoring and Energy Use
A pressure gauge does not measure energy. Pair pressure trends with true electrical input where possible and maintain the same process output. Calculate:
Energy use (kWh) = measured input power (kW) × operating hours
Different production modes should be calculated separately. A reduced power reading is not a saving if airflow, line speed or drying quality also falls.
Pressure monitoring can reveal restrictions that affect energy use, but it does not establish a saving by itself. Compare measured real input at equivalent accepted process output, accounting for resistance, controls and operating hours.
Build the Baseline During Commissioning
For each approved operating mode, record:
- all tagged pressure readings;
- instrument and calibration information;
- blower speed and active outlets;
- valve positions and filter differential;
- airflow or outlet-velocity data;
- voltage, current and true input power;
- air and ambient temperatures;
- product, line speed and acceptance result.
Set alarm thresholds only after considering normal variation and manufacturer limits. A poorly chosen alarm can either trip production unnecessarily or fail to detect a developing restriction.
Final Takeaway
The best blower pressure gauge location is the point that answers a specific operating question with repeatable data. Inlet and discharge taps characterize the blower, filter taps show loading, header taps reveal distribution pressure and branch taps help diagnose terminal performance.
Keep taps away from obvious flow disturbances, identify their pressure basis and preserve a commissioning map. A small number of well-planned measurement points is more valuable than many convenient gauges whose readings cannot be interpreted.
Frequently Asked Questions
Should the pressure gauge be installed at the blower outlet?
A discharge tap is useful, but it does not show downstream pressure after pipe losses or complete blower pressure rise when the inlet is below atmosphere. Additional points may be needed.
How should filter pressure drop be measured?
Use taps upstream and downstream of the filter and measure their differential pressure at a documented airflow or operating state.
Can a pressure tap be placed beside an elbow?
It is better to avoid that location because local swirl and pressure gradients may distort the reading. Use a representative straight section where practical.
Does every air knife need its own gauge?
Not always. Critical or adjustable branches benefit from comparable measurement points, while small systems may use temporary portable connections. Base the choice on diagnostic value.
What information should be written beside a gauge reading?
Record point tag, pressure type, reference, units, blower speed, active outlets, valve and filter condition, airflow data, instrument and process state.