QSL-68H Replaces Hanbell HBR-B05 on a Low-Temperature Screw Compressor

By Qishanr Technical Team · Published 14 September 2026
Customer field report · low-temperature screw compressor · long-run service

The Case at a Glance

What the Customer Reported

The source for this case is a single customer message, quoted in full:

“Used QSL-68H on Hanbell low-temp screw compressor, replacement of HBR-B05. Good oil return under low temperature, no sludge after long running.”

Two sentences, and both of them describe the same thing seen from different ends. Oil return is what the oil has to do at the cold end of the circuit; sludge is what it must not leave behind after a season of running. A low-temperature screw machine that gets both right is a machine whose oil, refrigerant and circuit are working together — which is what the rest of this page is about.

Why a VG68 POE Fits a Low-Temperature Screw Compressor

Same oil family, same viscosity grade

Hanbell HBR-B05 and Qishanr QSL-68H are both ISO VG68 polyol ester lubricants formulated for HFC refrigeration duty, so the change stays inside one chemistry family and one viscosity grade. On a screw compressor that matters twice over: the rotor pair relies on the oil for its sealing film as well as its lubrication, and the viscosity grade is part of how the machine was specified. Keeping family and grade identical is what makes the swap a like-for-like change rather than an experiment.

Why low-temperature duty is the hard case

In a comfort-cooling system the evaporator runs a few degrees below the space it serves, and oil that migrates into the circuit is warm enough to come back. On a low-temperature system the evaporating temperature is far lower, and the oil faces a different set of conditions at once:

• The oil is the coldest fluid in the room. Its viscosity rises as it cools, so anything that slows its flow back to the compressor is amplified.
• Refrigerant dissolves in the oil differently. Miscibility and the pour point of the mixture decide whether the oil arrives as a liquid that can be pumped or as a waxy mass that sits in the evaporator.
• Oil held in the wrong place costs twice. Oil that stays in the evaporator reduces heat transfer; oil that never returns starves the compressor bearings. The same litres cause both problems.
• Sludge has a colder place to form. Moisture, acid and varnish precursors concentrate where the circuit is coldest and the oil moves slowest.

That is why a low-temperature report is worth more than a comfort-cooling one. A customer who says the oil returns well at low temperature is describing the harder half of the duty.

Oil Return at Low Temperature: What Actually Decides It

Oil return is never the oil alone. It is the oil plus the circuit, and both halves have to be right.

The oil's half of the job

An ester for this duty needs a pour point well clear of the coldest surface it will meet, complete miscibility across the temperature range so the oil travels with the refrigerant instead of separating, and a viscosity that still forms a film at the bearings while staying thin enough to move. QSL-68H pours at −45 °C and carries a viscosity index of 114, which keeps its behaviour predictable as the circuit moves between pull-down and steady running.

The circuit's half of the job

Good oil return also depends on things no oil can change: adequately sized suction risers and traps that carry oil back at part load, a suction accumulator doing its job, a liquid line that feeds the evaporator properly, and a refrigerant charge that is not so far off that the machine spends its life at low load. When a system returns oil well, chemistry and circuit design agree with each other.

QSL-68H Reference Data

These are the QSL-68H reference values published in our refrigeration oil guides — the figures a changeover review starts from.

Full product details and packaging options are on the product page for Qishanr QSL-68H.

Replacing Hanbell HBR-B05: What the Cross-Reference Means

HBR-B05 is Hanbell's own ISO VG68 ester for its screw compressors. QSL-68H sits in the same family and the same viscosity grade, which is what makes it a usable cross-reference for plant already running a VG68 POE. Names buyers compare against QSL-68H in this grade:

• Hanbell HBR-B05
• Hanbell HBR-B03
• Emkarate RL68H
• CPI Solest 68
• Fusheng screw models on OEM POE VG68 (FS120R / FS150R / FS220R / FS300R)

Our QSL-68H cross-reference guide puts the three VG68 esters side by side, property by property, including the pour point difference that decides low-temperature oil return. Use it to slot QSL-68H against the oil already on your maintenance sheet.

Keeping a Low-Temperature Circuit Sludge-Free Over a Long Run

A clean oil at commissioning and a clean oil after a few seasons are two different achievements. These are the controls that keep a low-temperature machine on the right side of that line:

1. Keep the circuit dry. Evacuate properly and change filter driers on schedule — a hygroscopic ester with moisture in the circuit is the shortest route to acid and sludge.
2. Fix one grade and one source on the maintenance sheet so two oils never end up in the same machine.
3. Sample the oil at every service: level, colour, acid value and moisture. Two data points show a trend; one impression does not.
4. Watch the evaporator. A slow rise in approach temperature at a steady load usually means oil is collecting where it should not.
5. Hold superheat and charge in the specified window so the machine is not running permanently at low load.
6. Change the oil on the interval the operating profile justifies, not on a fixed habit carried over from a warmer duty.

Who This Case Fits — and Where to Choose Differently

Frequently Asked Questions

Can QSL-68H replace Hanbell HBR-B05?

Both are ISO VG68 polyol esters for HFC refrigeration, so the change stays within one oil family and one viscosity grade. Confirm the requirement against the compressor documentation and the refrigerant your plant runs, then release the oil change on those two facts.

Is QSL-68H suitable for low-temperature screw compressors?

Yes. Its −45 °C pour point keeps it flowing at the coldest point of a low-temperature circuit, it is fully miscible with the refrigerant so the oil travels back with the suction gas, and its 9.2 cSt at 100 °C holds the sealing film the rotor pair needs. It is used in screw compressors across low-temperature racks, cold stores and blast freezers.

How do I improve oil return in a low-temperature system?

Work both ends. On the oil side, pour point and miscibility set the floor. On the circuit side, check that suction risers and traps carry oil at part load, that the accumulator is doing its job, that the liquid line feeds the evaporator properly, and that charge and superheat keep the machine off permanent low load. Then sample the oil at service: the acid value and moisture tell you whether the circuit is staying clean.

What should I send with a QSL-68H enquiry?

The compressor brand and model, the refrigerant, the evaporating and condensing temperatures, the oil charge, the oil currently in the machine, your annual volume, preferred packaging, destination port and the documentation your maintenance team requires. With those details the reply comes back as an oil-change plan rather than a price for a drum.