IoT Pneumatic Line Pressure Monitor using ESP32

Pneumatic lines run factory automation — cylinders, grippers, blow-offs — and their health shows in one number: pressure. A slow leak wastes compressor energy and makes actuators sluggish; an over-pressure event risks burst fittings. Maintenance teams watch gauges, but gauges don't log, don't alert and don't count compressor cycles. This project instruments a small air line properly: an MPX5700 pressure sensor teed into the line, an ESP32 sampling it every second, and a dashboard showing a live gauge, the shift's pressure history, compressor cut-in/cut-out cycles and a leak-watch flag computed from pressure drop over 10-minute windows. A solenoid valve vents the line if pressure crosses the safety limit. The student learns pressure sensing, calibration against a gauge, threshold logic and the full IoT telemetry loop — on hardware that behaves like a real workshop line.

1. The MPX5700 sensor is teed into the small air line with pneumatic fittings; its analog output feeds the ESP32 ADC.
2. The ESP32 samples pressure every second, applies the two-point calibration, and publishes the reading over Wi-Fi (MQTT/HTTP).
3. The dashboard renders the live gauge, appends to the 8-hour history chart, and evaluates the reading each cycle.
4. Crossing the cut-out pressure logs a compressor stop; crossing cut-in logs a start — the cycle counter increments per hour.
5. Every 10 minutes the firmware computes the pressure drop; if it exceeds the leak threshold, the dashboard raises a leak-watch flag.
6. If pressure crosses the safety limit, the ESP32 energizes the solenoid valve to vent the line until pressure falls back.
7. The student introduces a controlled small leak (a loosened fitting) and watches the cycle count and drop metric respond.

Tech stack:

• ESP32 development board (Wi-Fi)
• MPX5700AP pressure sensor (0-700 kPa)
• Small air receiver / compressor line with analog gauge
• Solenoid valve for safety vent
• Pneumatic tubing and tee fittings
• MQTT broker + web dashboard (HTML/JS)
• Arduino IDE (C/C++ firmware)

• [MPX5700 pressure sensing] Piezoresistive sensor teed into the air line; ESP32 reads it every second through its 12-bit ADC.
• [Live gauge dashboard] Analog-style gauge plus digital readout, updating live over Wi-Fi with 8-hour pressure history.
• [Compressor cycle counting] Cut-in/cut-out detection counts cycles per hour — a rising count is the classic leak indicator.
• [Leak-watch detection] Pressure drop per 10-minute window is computed; crossing the leak threshold raises a watch flag on the dashboard.
• [Solenoid safety vent] On over-pressure the ESP32 drives a solenoid valve to vent the line — a demonstrable safety interlock.
• [Gauge calibration] The student calibrates the sensor reading against the analog gauge with a two-point procedure.
• [Shift event log] Compressor cycles, valve tests and leak watches are logged with timestamps.

• Working pneumatic pressure monitor (sensor node, line hardware, dashboard)
• Complete ESP32 firmware source code (sampling, calibration, MQTT, valve logic)
• Dashboard web app (gauge, history, cycle counter, event log)
• Plumbing and wiring documentation
• Two-point calibration procedure
• Leak-detection experiment guide
• Project report PDF (pressure sensing, pneumatics, IoT pipeline, experiment)
• PPT presentation for final review
• Viva Q&A preparation document (piezoresistive sensing, calibration, leak detection, MQTT)
• Setup and demonstration guide

• Demo-scale line only — small receiver and low pressures; not a plant air system and not rated for industrial pressures.
• Leak detection is indicative (pressure-drop heuristic), not a calibrated flow measurement; thresholds are set by the student's experiment.
• The solenoid vent is a demonstration interlock, not a certified pressure-relief device; a mechanical relief valve remains the real safety.
• Wi-Fi dropouts pause the dashboard feed; the node does not buffer long outages in the base build.
• Sensor accuracy follows the MPX5700 datasheet; the two-point calibration corrects offset and span on the student's rig.