Which connector does M8 Leak Detection Pigtail for CDU and Manifold Sensing use?

It is built around M8 3-position, or 2-position variants, to flying leads.

What jacket material does M8 Leak Detection Pigtail for CDU and Manifold Sensing use?

Plenum grade compound quoted in competitor data, pending confirmation of required rating.

What lengths does M8 Leak Detection Pigtail for CDU and Manifold Sensing come in?

Build lengths are 1 / 2 / 5 / 10 / 20 m.

M8 Leak Detection Pigtail for CDU and Manifolds

Last updated: 13 September 2026

Overview

Liquid cooling moved from a niche to a default faster than the cabling around it did. A coolant distribution unit, a rack manifold and the quick couplings on a cold plate all need to know whether fluid is where it should be, and that means a sensing circuit that routes into places a normal cable will not go and survives sitting next to glycol or a dielectric fluid for years. This M8 leak detection pigtail is the short assembly that joins the sensing element or point sensor to the monitoring input.

Key Specifications

Connector	M8 3-position, or 2-position variants, to flying leads
Function	Connection between leak sensing element or point sensor and monitoring input
Outer diameter	3.5 to 4.5 mm class (pending supplier datasheet)
Minimum bend radius	28 mm class (pending supplier datasheet)
Fluid compatibility	PG25 / LC25 glycol and dielectric coolant quoted in competitor data, pending immersion statement
Jacket fire rating	Plenum grade compound quoted in competitor data, pending confirmation of required rating
Standard lengths	1 / 2 / 5 / 10 / 20 m
Termination	Flying lead, tinned or ferrule, to customer specification
Typical uses	CDU cabinets, rack manifolds, cold plate couplings, underfloor loops
Compliance files	RoHS and UKCA documentation being collected, no marking claim made until held

What the pigtail actually does

Two things get confused in this category. A leak detection cable is the sensing element itself: a long run whose electrical behavior changes when fluid bridges it, which is also how the alarm is located along the run. A pigtail is not that. It is the connection between the sensing element or a point sensor and the monitoring input, and it has to be electrically boring: stable conductor resistance, a jacket that does not swell or leach into the coolant, and an outer diameter small enough to dress along a manifold. Most field problems with leak detection are not sensor failures, they are connection failures at this point.

Where the sensing points sit

Detection is only useful if it is placed where fluid actually escapes. This is the short list we see most often in a liquid cooled data hall.

Location	What you are watching	Routing note
CDU cabinet floor	Pump seal leak and drain pan overflow	Dress to the low point, not to the cable tray
Rack manifold and blind-mate couplings	Weep at a coupling that has not fully seated	Keep the bend off the coupling body
Cold plate inlet and outlet	A quick coupling that has backed off a turn	Slim jacket, tight bend radius
Underfloor loop and containment	Fluid migrating away from the rack	Run the sensing element along the whole path
Heat exchanger and filter skid	Gasket seep during maintenance	Leave service length for filter changes

M8 pigtail wiring

Three positions is the usual build: two for the sensing loop and one for the screen or a spare. Two-position variants exist where the sensor is a simple contact closure.

Pin	Color	Function	Termination
1	Brown	Sensing loop A	Tinned, ferrule or to your specification
2	White	Sensing loop B	Tinned, ferrule or to your specification
3	Blue	Screen or spare conductor	Tinned, ferrule or to your specification

The connector end is chosen to match the sensor or the controller you already have. If the monitoring panel is on an M12 interface, this is the family you are connecting into.

Code	Contacts	Carries	Typical voltage	Relevance here
A	3 to 12	Sensor signals	30-250 V	Most point sensors and controllers
D	4	100 Mbit/s Ethernet	60 V	Controller uplink, not the sensor
B	4 to 5	PROFIBUS-DP	60 V	Rare in a data hall
C	3 to 6	AC power	250 V AC	Pump and heater supplies
X	8	10 Gbit/s Ethernet	60 V DC	Not used for sensing
L	4+FE	DC power	63 V DC	CDU internal 24 V distribution
T	2 to 4	DC power	63 V DC	Pump drives
K	4+PE	Three-phase AC	630 V AC	Pump motors
S	2+PE / 3+PE	Single-phase AC	630 V AC	Mains feed to the CDU
M	5 to 6	Servo power	630 V AC	Not used here
P	4	EtherCAT P	60 V	Not used here
Y	8 (4+4)	Power plus data	50 V	Not used here

Fluid compatibility is the hard requirement

Coolant loops run on inhibited glycol mixtures, typically a propylene glycol blend of the PG25 or LC25 type, or on a dielectric fluid in direct-to-chip systems. A coolant that is harmless to mineral oil rated cable can soften, crack or leach plasticizer out of a jacket, and leached material ends up in a cold plate channel or a filter. Competitor data claims compatibility with both fluid families; that claim depends on the exact compound and the exact fluid, and it needs a supplier immersion statement before it goes into a data hall design.

Size and fire rating

Outer diameters in the 3.5 to 4.5 mm range and a minimum bend radius around 28 mm are quoted for comparable products. Those dimensions matter more than they look: a pigtail that will not turn the corner behind a manifold gets forced, and a forced cable lifts a coupling. Where the run leaves the rack for a plenum or a raised floor return, the jacket fire rating becomes a building requirement rather than a preference.

What we are confirming

Outer diameter, bend radius, conductor gauge, fluid compatibility and jacket fire rating for this range come from public competitor data, not a verified datasheet for our part. Lengths run from 1 to 20 m with a flying lead or a two or three position connector on the sensing end.

Typical applications for this M8 leak detection pigtail

Coolant distribution unit cabinets and pump skids
Rack manifolds and the blind-mate couplings at the rear of a rack
Cold plate inlet and outlet couplings on GPU and CPU trays
Underfloor loops and containment areas where a slim run is easier to dress

How to specify your build

Connector – M8 3-position, 2-position, or flying lead both ends.
Fluid – glycol blend or dielectric, and the product name.
Length and the tightest bend the routing demands.
Fire rating required for where the run leaves the rack.
Termination – tinned, ferrule, or a specific contact.
Quantity, prototype or production.

Workmanship and testing

Cable assemblies here are built to IPC/WHMA-A-620 Class 3 workmanship inside an ISO 9001 system, across a 32 to 12 AWG range. Continuity and pinout are verified on every unit before packing. Seal checking on the batch can be quoted when an ingress rating is specified.

Custom builds and ordering

Prototype quantity starts at 5 pcs with a 3 working day turnaround, and production starts at MOQ 500 pcs shipping 14 working days after approval. Where a new tool is needed, allow about 10 working days. We ship OEM and ODM builds under your part number and labeling, and can provide material certificates and first-article reports.

Related sensing and circular assemblies

Full range: circular M8 and M12 cable assemblies.

Frequently Asked Questions

Is this the sensing cable itself?

No. The sensing cable is the element that changes behavior when fluid bridges it. The pigtail connects that element, or a point sensor, to the monitoring input.

Which fluids is the jacket compatible with?

Competitor data covers inhibited glycol blends and dielectric fluids. The claim depends on the exact compound and the exact fluid, so we ask for a supplier immersion statement before it goes into a design.

How slim can you build it?

Comparable products quote 3.5 to 4.5 mm outer diameter and around 28 mm minimum bend radius. Tell us the tightest bend in the routing and we will confirm what the jacket will take.

Connector

M8 3-position, or 2-position variants, to flying leads

Function

Connection between leak sensing element or point sensor and monitoring input

Outer diameter

3.5 to 4.5 mm class

Minimum bend radius

28 mm class

Fluid compatibility

PG25 / LC25 glycol and dielectric coolant class

Jacket fire rating

Plenum grade compound