Bypass Device
In air tightness testing, large‑volume workpieces (e.g., battery packs, fuel tanks, large housings) often require a long filling time – gas must slowly fill the entire cavity, significantly increasing the test cycle time and becoming a bottleneck for production line efficiency. The AMT Bypass Device is specifically designed to solve this problem. By adding a large‑bore fast‑fill branch in parallel with the main test circuit, it greatly increases the flow rate during the initial filling phase. When the pressure approaches the target value, the device automatically switches back to the precision test circuit, achieving an ideal balance between “fast filling” and “accurate detection”. The Bypass Device has a stand‑alone box design, internally integrating a large‑bore pneumatic valve, a check valve, and a control unit. In use, it is connected in series between the tester outlet and the workpiece. The bypass valve is opened and closed via I/O signals from the PLC or the tester itself. The compact, plug‑and‑play design requires no complex modification of the existing test system.
Main parameters
Technical Specifications
| Parameter | Description |
|---|---|
| Working pressure range | -0.1 ~ 1.6 MPa |
| Bypass bore size | 6 mm / 10 mm / 15 mm (optional, matched to volume) |
| Main path bore size | 4 mm / 6 mm |
| Max filling flow rate | 3000 L/min (@0.6 MPa, 10 mm bore) |
| Switching pressure point | Programmable as 85%～95% of test pressure (controlled by PLC or instrument program) |
| Port type | Quick‑connect fittings (inlet/outlet); threaded optional |
| Control signal | 24V DC, NPN/PNP compatible |
| Response time | Bypass valve open ≤0.1 sec, close ≤0.2 sec |
| Enclosure material | Aluminum alloy + powder coating |
| Protection rating | IP50 |
Technical Advantage
Key Advantages
Dramatically reduces filling time
The bypass bore can be 3–5 times larger than the main path, increasing filling flow by over 300%. For large‑volume workpieces >100 L, filling time can be reduced from tens of seconds to a few seconds, significantly improving the test cycle.Does not affect test accuracy
The bypass is open only during the fast‑fill phase. Once the pressure reaches a preset threshold (typically 90%–95% of the test pressure), the bypass automatically closes and the system switches to the precision test circuit. Subsequent hold and measurement phases are still performed by the tester’s high‑precision sensors, so leak judgment accuracy remains unaffected.Stand‑alone box, plug‑and‑play
Standard quick‑connect inlet/outlet ports allow direct connection to AMT series air tightness testers and workpieces. The small box can be mounted on the side of equipment or on a production line frame.Automatic control, seamless integration
Provides digital I/O interface (NPN/PNP compatible) for connection to the tester or PLC. No manual intervention is needed; the test program automatically manages bypass opening and closing.Safe and reliable with multiple protections
A built‑in check valve prevents backflow of gas from the workpiece. The bypass valve is a pilot‑operated pneumatic valve, providing fast response and reliable sealing. Even in the event of an unexpected air supply loss while the bypass is open, the workpiece pressure will not drop suddenly.
Typical Application Scenarios
| Workpiece Type | Typical Volume | Filling Time Without Bypass | Filling Time With Bypass |
|---|---|---|---|
| NEV battery pack | 80～200 L | 30～60 sec | 5～10 sec |
| Large fuel/water tank | 50～100 L | 20～40 sec | 3～8 sec |
| Outdoor AC unit housing | 30～50 L | 15～25 sec | 2～5 sec |
| Industrial tank/piping system | >100 L | >60 sec | 10～20 sec |
Operation Procedure
Connect the bypass device inlet to the tester outlet, and the outlet to the workpiece.
Connect the control cable to the designated output port of the tester or PLC.
In the test program, set the “bypass close pressure threshold” (e.g., close bypass when 90% of target pressure is reached).
Start the test: the tester first opens the bypass valve for fast filling → when the threshold is reached, the bypass closes and the system switches to the precision test circuit → complete hold, measurement, and exhaust.
Selection Guide
Small volume workpieces (<10 L): Bypass not needed, or use the smallest bore.
Medium volume (10～50 L): A 6 mm bore bypass noticeably accelerates filling.
Large volume (50～200 L): Recommend 10 mm or 15 mm bore, with quick‑connect fittings.
Extra‑large volume (>200 L): Custom dual‑bypass or larger bore solutions available.
Stop waiting for gas in large‑volume testing.
AMT Bypass Device – fast filling for high‑efficiency lines, precision testing for quality protection.
Application Field
Automotive Industry
New Energy Batteries & Energy Storage
Aerospace & Defense
