Separator run — Inzonex Modular Insulation, hot-water skid
Dirt separator / Servicing
Servicing a dirt separator
It takes out what a sieve never could, and it fills up out of sight.
A strainer stops what will not fit through its mesh. A separator does something a mesh cannot. It slows the water enough for magnetite and fine sludge to fall out of suspension and collect in the bottom. Nothing about that is visible from outside, and the only sign it is full is that it has stopped working.
What it collects
And why a strainer will not do it
Magnetite
Iron oxide from ordinary corrosion inside a closed system, fine enough to pass any practical mesh and heavy enough to settle when the water slows. It is what blackens the water on a system that has never been cleaned.
Fine sludge
Corrosion product, jointing compound and whatever else the circuit has picked up, ground fine by years of circulation. It is the material that ends up in plate channels and in pump bearings.
Which is why both are fitted
On this skid the Y-strainer is upstream and takes the coarse debris; the separator sits behind it and takes what got through. Neither replaces the other.
Draining
The whole of the maintenance
On a cycle, not on a fault
The drain valve at the bottom is cracked open and the collected sludge let out. It is a minute of work and it is the reason the unit is there. Left undone, the collection volume fills and the separator becomes a piece of pipe with a pressure drop.
Vent at the top
The unit holds its charge at line temperature and needs venting after any work that has let air in. Both valves are small and both are left outside the module.
A magnetic unit needs the rod cleaned
Where a magnet is fitted it holds the magnetite against the wall, and the rod is withdrawn and wiped as part of the same visit. That access has to stay clear too.
The drain leg
Where corrosion starts
It runs cold and wet
Below the separator the leg is out of the flow, so it is cooler than the shell and it stays damp from every drain-down. That combination under a covering is where corrosion under insulation begins.
So it is treated differently
The leg is inspected rather than simply covered, and the drain valve stays exposed. Covering it would hide the one place on the unit worth looking at.
For insulation
A vessel with two small exceptions
The shell is the easy part
Shell and both heads sit at line temperature with no gradient worth speaking of. The unit loses far more than the pipe either side of it.
The vent and the drain are the hard part
Both are operated on a cycle. They stay outside the module, so the separator can be vented and drained without anyone touching the insulation.
Reference
Symptom against cause
| Symptom | What it usually means | What to do |
|---|---|---|
| Pressure drop rising across the unit | Collection volume filling | Drain it before looking further |
| Water still black after cleaning | Magnetite generating faster than removed | System water treatment, not the separator |
| Nothing comes out of the drain | Drain leg blocked with settled sludge | Rod it through; do not assume the unit is clean |
| Air noise after a drain-down | Unit not vented on refill | The vent on top, before the pump runs |
Symptom · What it usually means · What to do
Asked about servicing a dirt separator
Questions.
Answers distinguish modelled heat-loss estimates from equipment selection and service guidance.
What does a dirt separator do that a strainer does not?
It slows the water enough for magnetite and fine sludge to drop out of suspension. Those particles pass straight through any practical mesh, so a strainer never sees them. The strainer takes the coarse debris upstream; the separator takes what got through.
How often should a dirt separator be drained?
On the same cycle as the rest of the plant inspection, and always after work that has disturbed the system. It is a minute of work at the drain valve. Left undone the collection volume fills and the unit stops doing anything.
Why does the drain leg on a separator corrode?
It sits out of the flow, so it runs cooler than the shell, and it stays damp from every drain-down. Cool and wet under a covering is exactly where corrosion under insulation starts. The leg is inspected rather than simply wrapped.
Can a dirt separator be insulated?
The shell and both heads, yes, and they are the part worth covering because they sit at line temperature across their whole area. The vent at the top and the drain at the bottom stay outside the module so the unit can still be vented and drained.
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More on dirt separator
The node page carries the heat-loss figures and the size table.