- Vertical oil recovery: ideal for sumps, tanks, settling ponds, API separators, and any quiescent zone where hydrocarbons collect on the water surface.
- Two models: RS-31 (fixed speed, 13.5/27/40 RPM) and RS-31V (variable speed, 0–22 RPM with controller).
- Both use a 4″ oleophilic mop (HW-4) — high-quality polypropylene fibers that attract oil and reject water.
- Recovery rate: up to 100 gallons per hour at top speed (varies with oil type and viscosity).
- Up to 30 ft of mop length — long reach for ponds, basins, and remote sumps.
- Compact: 13″ L × 14″ W × 22″ H. RS-31: 55 lbs. RS-31V: 50 lbs.
- Simple mounting — suspend by handle or hard-pipe into the 2″ oil discharge fitting at the base.
- Industrial proven — installed at Duke Power and at oil/water sites across multiple industries.
IN STOCK. READY TO SHIP. SIMPLE OIL REMOVAL.
Got an oily water problem? We keep RS-31 mop wringers ready so you can mount, run mop, and start recovering — no long lead times.
Rope Mop Oil Skimmer Features
01
Design
- Compact frame: 13″ L × 14″ W × 22″ H — drops in over almost any sump, tank, or pond access.
- Two 3″ diameter squeeze rollers extract recovered oil from up to 30 feet of HW-4 mop.
- 2″ NPT pipe fitting at the base — suspend the unit from its handle or hard-pipe directly to a storage drum.
- Bolted-frame, gear-driven design — minimal moving parts, easy to maintain in industrial environments.
- Standard configuration uses the 4″ HW-4 handwoven polypropylene mop. Larger handwoven mops (HW-6, HW-9, HW-12, HW-18) and belt-sewn mops (BS-3 through BS-12) available as accessories.
02
PERFORMANCE
- Recovery rate: up to 100 GPH at top speed.
- Actual recovery varies with oil type and viscosity — heavier oils typically yield higher pickup per pass; lighter oils benefit from slower speeds.
- Slower / intermittent operation: when oil recovery requirements are only a few gallons per day, the variable-speed RS-31V or a timer on the fixed-speed RS-31 prolongs component life.
- 30 ft mop reach — works in deep tanks, large basins, and elevated mounting positions.
03
RS-31 (Fixed Speed) vs RS-31V (Variable Speed)
| Spec | RS-31 (Fixed Speed) | RS-31V (Variable Speed) |
|---|---|---|
| Motor | 1/12 HP, TEFC | 1/8 HP, 90V DC with variable-speed controller |
| Power | 110 / 220V, 50 Hz | Variable speed controller (115V, 60 Hz) |
| Speed | 13.5 / 27 / 40 RPM (3 fixed speeds) | 0 – 22 RPM (variable) |
| Dry Weight | 55 lbs | 50 lbs |
| Dimensions | 13″ L × 14″ W × 22″ H | 13″ L × 14″ W × 22″ H |
| Max recovery | Up to 100 GPH | Up to 100 GPH (at top speed) |
03
Installation & Operation
- Mount the RS-31 directly above the area to be skimmed — high enough for the mop to free-fall to the liquid surface and the recovered oil to gravity-drain to a container.
- Mount by suspension from the handle , OR hard-pipe to the 2″ NPT fitting in the base.
- Feed the HW-4 mop over the front guide roller , through the squeeze rollers, over the rear guide roller, then splice the free ends together with square knots through the floating pulley loop.
- Aim for 2–6 ft of mop in contact with the water surface. Longer lengths can tangle and damage the wringer.
- For installations where liquid level varies more than 3 ft, spread the mop over the surface area to avoid mop build-up beneath the wringer.
- Adjust the front guide roller so the incoming mop passes through the wringer with minimum oil loss as it’s squeezed.
WHY ROPE MOP SKIMMERS STILL GET USED
Crude? Yes. Effective? Absolutely. Rope Mop Skimmers are old-school but incredibly reliable in the right situations — especially when you’re dealing with open water, tricky angles, or a lot of surface area. Even if the oil’s tough to grab, these machines can still collect it. Sometimes, simpler is smarter.
Floating Pulleys
Use floating pulleys to guide the mop across the water surface in tanks, ponds, or basins. Galvanized steel sheaves with replaceable nylon bearings — no lubrication required.
| Model | Pulley Diameter | Compatible Mop Diameter |
|---|---|---|
| SFP-12 | 12" | 4", 6" |
| SFP-16 | 16" | 4", 6" |
| SFPN-16 | 16" | Extra-flotation N-series |
| SFP-24 | 24" | 4", 6", 9" |
| SFPN-24 | 24" | Extra-flotation N-series |
Oleophilic Mop
- Handwoven (HW): Mops are made by manually braiding the fibers into a polypropylene rope core (3/8″–3/4″ diameter). Available in 4″, 6″, 9″, 12″, and 18″ diameters.
- Belt-Sewn (BS): Mops use a 1/2″–1″ wide belt as the central core to which fibers are sewn. Available in 3″, 4″, 6″, 9″, and 12″ diameters.
| Property | Value |
|---|---|
| Composition | Fibrillated polypropylene |
| Specific gravity | 0.90 (floats) |
| Temperature range | 40 °F – 210 °F |
| UV resistance | UV inhibitors added |
| Chemical resistance | Unaffected by mild acids or alkalis; salt water — no adverse effect |
| Color | White |
| Shelf life | Indefinite (clean & dry storage) |
- Cleaning: soak or rotate the mop through a petroleum-based solvent, then squeeze through the wringer rollers. High-pressure or steam cleaning will “fluff” fibers and remove embedded grit.
- Detergents are NOT recommended — coating the fibers with detergent will lessen oil-attracting capability.
- Storage: rope mops can be stored indefinitely in a drum or storage bag. Avoid temperatures above 210 °F or below −40 °F.
- Dirty mops with flammable hydrocarbons are a fire hazard — store with the same care as the hydrocarbons themselves.
WHY THE RS-31 ROPE MOP MATTERS
Rope mop skimmers have been a workhorse of industrial oil recovery for decades. The RS-31 is a compact, low-power, low-maintenance unit that drops in over a sump or tank and recovers floating oil with almost no operator intervention. When you don’t need the throughput of a belt skimmer or weir skimmer, and you want something that handles long mop runs and irregular tank shapes, the RS-31 is the right tool.
Field-Proven
RS-31 units have been deployed across industrial sites — including work for Duke Power. Typical applications include settling ponds, sumps, basins, API separators, and any quiescent zone where hydrocarbons collect.
How the Rope Mop Skimmer Works
The mop is fed in a continuous loop through the wringer’s squeeze rollers and across the water surface (often guided by floating pulleys). As the loop moves, the oleophilic mop fibers contact floating oil — oil clings to the fibers, water sheds off. The mop is then pulled up through the wringer where two 3″ rollers squeeze the oil out of the fibers and into the 2″ gravity-drain fitting at the base. The clean mop continues back to the water surface for another pass — continuous, automatic operation.
Frequently Asked Questions
How much oil can the RS-31 recover?
Up to 100 gallons per hour at top speed. Actual recovery varies with the oil type — heavier oils typically yield higher pickup, lighter oils benefit from slower mop speeds. The variable-speed RS-31V lets you match the speed to the oil and the application.
How much mop length can the RS-31 handle?
Up to 30 feet of HW-4 mop. Aim to keep 2–6 feet in contact with the water surface — longer can tangle and damage the wringer.
What's the difference between the RS-31 and RS-31V?
Same frame, same 1/2 HP motor, same dimensions. The RS-31 has 3 fixed speeds (13.5, 27, 40 RPM). The RS-31V has a variable-speed controller (0–22 RPM) — useful when oil flow varies, when slow speeds prolong component life, or when you only need a few gallons per day.
Can I use a different mop size?
The RS-31 ships configured for the HW-4 (4″ handwoven) mop. Other SkimOIL ® mop sizes are available as accessories — handwoven HW-6 / HW-9 / HW-12 / HW-18 and belt-sewn BS-3 through BS-12 — but check with us first to confirm fit and squeeze-roller compatibility for your specific configuration.
How is the recovered oil collected?
A 2″ NPT fitting in the base of the unit gravity-drains the recovered oil to wherever you route it — a 55-gallon drum, an oil storage tank, or back into a process. No pump required for the oil collection itself.
Do I need to run it continuously?
Usually no — for many applications all the floating oil is removed in a short period of operation. We recommend a timer to run the wringer at intervals or scheduled times. The RS-31 should not be left running unattended overnight or over weekends.
Will the mop float?
Yes — the polypropylene fibers have a specific gravity of 0.90, so the mop floats on water. UV inhibitors are added for outdoor use, and the mop is unaffected by salt water and mild acids or alkalis.
How do I clean the mop?
Soak or rotate the mop through a petroleum-based solvent, then run it through the squeeze rollers. Avoid detergents — they coat the fibers and reduce oil-attracting capability. High-pressure or steam cleaning is also fine and helps remove embedded grit.
Why rope mop skimmers still work
- Excels in harsh, debris-filled environments
- High oil recovery—up to 20 GPM
- Runs unattended with simple motor power
- Durable build for industrial use