A small hydraulic leak rarely stays small. Oil escapes at one fitting, runs along a hose, gets blown around by a cooling fan and collects dirt, and by the time anyone notices, the whole side of the machine is wet. Finding where it started can take hours of cleaning down and waiting. Fluro dye takes most of the guesswork out of the job.
ILS now stocks the Spectroline range of fluorescent leak detection dyes and UV lamps. This guide explains how fluro dye works, which colour to choose, and how much to add.
How fluro dye works
Fluorescent leak detection is a three-step process.
- Add the dye. A small, measured amount of fluro dye goes into the system, usually through the fill point.
- Let it circulate. Run the equipment so the dye mixes through the fluid. Depending on the size of the system, this takes from a few minutes to a few hours.
- Scan with a UV lamp. Shine a UV or violet leak detection lamp over the equipment. Wherever fluid is escaping, the dye glows brightly, right at the source.
Because the dye stays in the system, it keeps working. Spectronics, the maker of Spectroline, recommends dosing equipment before you have a problem, so a technician can check for leaks in seconds during routine servicing.
Where it is used
Fluro dye works in any closed-loop system where fluid circulates. Typical uses include:
- Mobile hydraulic equipment: earthmoving and construction plant, agricultural machinery, forklifts and hydraulic lifts
- Stationary hydraulics: presses, shears and benders, dock levellers and vehicle hoists
- Plant maintenance: injection moulding, stamping, compressors, gearboxes and power generation
- Coolant and water systems: glycol cooling circuits, boilers, heat transfer systems and sprinkler lines
It is also used by equipment manufacturers on the production line to check new engines and hydraulic cylinders before they leave the factory.
Choosing the right colour
Spectroline makes several colours so you can code different systems on the same machine. If the hydraulics are dosed green and the engine is dosed yellow/green, a technician can tell straight away which fluid is leaking.
| Product | System | Glows | Lamp |
|---|---|---|---|
| Yellow Green Fluro Dye (Oil) 473 mL | Oil, hydraulic, fuel | Yellow/green | UV or violet |
| Yellow Green Fluro Dye (Oil) 948 mL | Oil, hydraulic, fuel | Yellow/green | UV or violet |
| Green Fluro Dye (Oil) 473 mL | Oil, hydraulic | Green | UV or violet |
| Yellow Fluro Dye (Oil) 473 mL | Oil, hydraulic | Yellow | UV |
| White Fluro Dye (Oil) 473 mL | Oil, hydraulic | Blue-white | UV |
| Green Fluro Dye (Water) 473 mL | Water, glycol coolant | Green | UV or violet |
If you only want one colour for oil systems, start with yellow/green. It works with both lamp types and is the only oil dye in the range also suitable for petrol and diesel. For coolant and water leaks, use the water dye. Oil dyes will not mix into water-based fluids.
How much dye to add
Dose rates depend on the fluid. Darker and heavier oils need more dye to give a clear glow. These rates come from Spectroline.
| Fluid | Dose |
|---|---|
| Light-coloured hydraulic fluid | 30 mL per 30 L (about 200 mL per 205 L drum) |
| Dark hydraulic fluid | 30 mL per 15 L |
| Compressor oil | 30 mL per 15 L |
| Engine oil | 30 mL per 11 L |
| Gearbox oil | 30 mL per 4 L |
| Petrol or diesel (yellow/green only) | 30 mL per 45 to 68 L |
| Water or glycol coolant (water dye) | 473 mL per 3,785 L |
The twin-neck bottles have a measuring chamber built in, so you can pour an accurate dose without a separate jug.
Will the dye affect my oil?
It is a fair question. According to Spectronics, Spectroline dyes are fully miscible, contain no co-solvents and are filtered down to 2 microns, so they add no particles to the system. Spectronics states they do not change the viscosity, lubricity or other properties of the host fluid and can safely stay in the system indefinitely. The dyes are also NSF registered for non-contact food-grade use.
Dye concentration matters. A weak dye needs more product and still gives a dull result. Spectroline dyes are concentrated, which is why a small dose is enough.
If you are dosing equipment that is under warranty or on an oil analysis programme, talk to us first and we can confirm suitability for your application.
Lamps and safety glasses
The dye only glows under the right light. Spectroline LeakTracker lamps use a 365 nm UV LED and can pick up a leak from up to 8 metres away, depending on light levels. Always wear UV-absorbing safety glasses when using a UV lamp.
The easiest way to get started is the Spectroline LeakTracker Complete kit. It includes a LeakTracker MINI UV lamp, a bottle of yellow/green oil dye, UV glasses, GLO-AWAY PLUS dye cleaner to clean the leak site after repair, and labels to mark which equipment has been dosed.
Frequently asked questions
How long does it take to find a leak with fluro dye?
On most equipment, the dye circulates within minutes to a few hours. Once circulated, scanning takes seconds. Very slow leaks may need the machine to run for a shift before the glow builds up.
Can I use fluro dye in a hydraulic system that is running?
Yes. Add it at the fill point and run the system normally. The dye is designed to circulate with the fluid.
Do I need to drain the dye out after the repair?
No. The dye can stay in the system and will show up any future leak. Clean the dyed area after the repair so old residue is not mistaken for a new leak.
What is the difference between fluro dye and fluoro dye?
Nothing. Both are short for fluorescent dye. “Fluro” is the common spelling in New Zealand and Australia.
Get the right dye for your site
The full Spectroline range is available from ILS. Browse the Spectroline brand page or contact your ILS territory manager to work out the right dye, colour and lamp for your plant or fleet.