Panasonic SQ4-A21-P Safety Liquid Leak Sensor PNP

Technical Overview

Safety liquid leak sensor with PNP output, 12-24VDC, IP62 polypropylene housing, and two-stage detection for standard liquids.

Key Features

Designed for safety leak detection in standard liquids.
Achieves SIL3 safety integrity level when used with a Panasonic controller.
Meets Category 4, PLe, SIL3 when used with SQ4-C11 safety controller; meets Category 1, PLc, SIL1 standalone.
Constructed with a durable polypropylene enclosure.
Pre-wired with a 2m 4-core 0.18mm2 PVC cabtyre cable.
Provides a digital PNP open-collector output (24Vdc / 50mA).
Offers IP62 degree of protection.
Incorporates two-stage detection for incipient and abnormal liquid leaks.
Capable of detecting human error (improper installation) and sensor malfunctions.
Utilizes an Infrared LED (modulated) as the sensing source.
Operates with a supply voltage of 12 to 24VDC.
Operational temperature range from -10 to +55° C.

Technical Specification Matrix

Parameter	Value
Sensing Type	Liquid leak detection sensors for standard liquids
Sensing Source	Infrared LED (modulated)
Supply Voltage	12 to 24VDC
Current Consumption	30 mA
Control Output	PNP x 2 (open-collector, 24Vdc, 50mA)
Output Mode 1	On when no liquid present, OFF when leakage detected or wrong installation
Output Mode 2	ON when normal condition, OFF when initial detection or accidental leakage
Response Time (Out 1)	10 ms
Response Time (Out 2)	50 ms
Operating Temperature	-10 to +55° C
IP Rating	IP62
Enclosure Material	Polypropylene
Cable Type	4-core 0.18mm2 PVC cabtyre cable
Cable Length	2 m
Terminal Type	Bare flying leads
Physical Weight (kg)	0.05
Dimensions L x W x H (cm)	0 x 3.58 x 1.57

Industrial Applications

1. Automated Machine Tool Coolant Leak Detection

The SQ4-A21-P can be strategically positioned around the base or coolant reservoirs of CNC machining centers to detect coolant leaks. Its compact size facilitates installation in confined spaces, preventing hazards and equipment damage.

Problem Solved

Prevents accumulation of coolant, reduces slip hazards, protects electronic components from liquid damage, and minimizes production interruptions by providing early warning of leaks. The IP62 rating offers adequate protection against typical industrial splashing.

CNC machiningcoolant managementleak preventionindustrial safetyearly warning systemsIP62polypropylene housing

2. Water Treatment Plant Sump Monitoring for Overflow Prevention

In water treatment facilities, the sensor can monitor liquid levels in critical sumps or tanks, providing a two-stage alert system to prevent overflows that could lead to environmental contamination or facility damage.

Problem Solved

Detects rising water levels (incipient overflow) to trigger alarms and higher levels (abnormal overflow) for emergency shutdowns, preventing spills and costly cleanups. The 12-24VDC operation is standard for industrial control systems, and SIL3 capability (with a controller) ensures high reliability for critical applications.

Water treatmentsump monitoringoverflow detectionenvironmental protectionindustrial automationSIL312-24VDCtwo-stage detection

3. Semiconductor Manufacturing Equipment Drip Tray Monitoring

For cleanroom environments in semiconductor fabrication, this sensor can be installed in drip trays beneath critical processing stations to detect minor leaks of process liquids (standard liquids) which could compromise product quality.

Problem Solved

Provides rapid and reliable detection of liquid accumulation in drip trays, preventing contamination of wafers and damage to sensitive electronics. The early detection feature is vital for maintaining pristine cleanroom conditions and preventing catastrophic failures. Its small footprint is ideal for integration into confined equipment spaces.

Cleanroomsemiconductor fabricationprocess fluid leakcontamination controlequipment protectiondrip tray monitoringcompact sensorrapid response