What It Is

The YEJ series is a mechanical pressure gauge designed for low‑pressure and negative‑pressure (vacuum) measurement of neutral, non‑corrosive gases. It uses a sensitive capsule element – not a common Bourdon tube – so it can measure down to just a few hundred pascals.

The rectangular case fits neatly into control cabinets or tight panels.

Two Models – Pick What You Need

YEJ‑101 (Indicator only)

• Pure mechanical indication – no electricity required

• Easy to read, always works even during a power outage

• Best for on‑site monitoring of boiler air supply, flue gas ducts, or ventilation systems

YEJ‑121 (With electric contacts)

• Adds preset upper and lower limit contacts

• Can directly trigger alarms, relays, or PLC inputs

• Great for automatic pressure control or safety interlocking

Key Features (No Jargon)

• Sensitive to very low pressure – Works perfectly where ordinary gauges show no movement

• Low air intake – Does not disturb the system being measured

• Rectangular housing – Space‑saving, stable, and vibration‑resistant

• YEJ‑121 contact capacity – 3A 220V AC, enough for most alarms and small relays

• Wide pressure range options – From –250 Pa up to 60,000 Pa (positive, vacuum, or compound)

Typical Applications

• Boiler combustion air monitoring

• Flue gas duct pressure (draft measurement)

• Cleanroom differential pressure

• HVAC air filters and duct static pressure

• Dust collection systems

• Laboratory test benches for low‑pressure gases

Simple Specs (No Table)

• Accuracy: 2.5% of full scale

• Pressure connection: φ8 tube (fits φ6 inner diameter hose)

• Operating temperature: –20°C to +60°C

• Humidity: ≤85% RH

• Weight: YEJ‑101 ~2 kg ; YEJ‑121 ~2.5 kg

• Power (YEJ‑121 only): AC 220V, <5W

Why Choose YEJ?

• No external power for YEJ‑101 – truly independent mechanical gauge

• Easy to mount – rectangular shape fits flat panels

• Reliable in vibration – less pointer drift than round gauges with the same mechanism

• Contact version saves cost – no need for a separate pressure switch