The IPS2050-40 OS-40L is Benchmark Industrial's 40-liter capacity overhead stirrer — the higher-torque, higher-viscosity-ceiling sibling of the OS-20L (IPS2050-20). Where the OS-20L caps at 10,000 mPa·s viscosity in a 20 L vessel, the OS-40L delivers 50,000 mPa·s capability in a 40 L vessel — a 5× step-up in viscosity ceiling that handles the workflows magnetic stirrers and lower-torque overhead mixers can't reach: high-viscosity formulation development, large-volume cosmetic and personal-care mixing, mid-scale pharmaceutical pilot-line work with semi-solid or paste-class viscosities, and process-development workflows where vessel volume exceeds 20 L. Like the OS-20L, the OS-40L ships with complete stand assembly + mounting hardware plus a 4-arm stainless steel propeller (IPS2050-P-S4).
Voltage options: This unit can be ordered with European voltage requirements (230V/50Hz). Contact us to order.
Key Specifications
| Mixing capacity (water-equivalent) | 40 L |
| Maximum viscosity | 50,000 mPa·s |
| Maximum torque | 60 Ncm |
| Speed range | 30 – 2,200 rpm |
| Motor type | DC Brushless |
| Input power | 120 W |
| Output power | 100 W |
| Net weight (mixer head) | 2.8 kg |
| Maximum vessel height | 24 inches |
| Voltage | 100 to 240 V (universal); 50/60 Hz |
| Display | LCD control panel; speed and run time set + monitored |
| Included | OS-40L mixer head + complete stand assembly + mounting hardware + 4-arm stainless steel propeller (IPS2050-P-S4) |
Application Profile
High-viscosity pharmaceutical formulation. Semi-solid and paste-class formulations (creams, ointments, gels at high solids loading) where the OS-20L's 10,000 mPa·s ceiling would be insufficient. The OS-40L handles formulations up to 50,000 mPa·s in 40 L vessels.
Cosmetic and personal-care production-scale mixing. Cream, lotion, and emulsion mixing at the 30–40 L pilot-batch scale with viscosity-rising profiles through the mix cycle as ingredients are added.
Industrial-process suspension at production volume. Pre-mix preparation for production-feed streams in 30–40 L vessels — particulate suspension, polymer dispersion, slurry preparation.
Food-science mid-scale R&D. Beverage R&D, sauce and emulsion development, and food-suspension prep at vessel volumes that exceed the OS-20L's range.
Brewing / fermentation pilot work. Wort mixing at the 30–40 L pilot-batch scale, fermentation prep, and ingredient suspension in larger pilot fermenters.
Aqueous-organic reaction agitation. Lab-scale chemistry reactions in 30–40 L vessels where viscosity rises significantly through the reaction time — the 60 Ncm torque maintains agitation under load that lower-torque mixers would stall against.
Pharmaceutical and biotech downstream prep. Larger-vessel resuspension of dried protein products, bulk-suspension prep before downstream filtration or centrifugation.
Design Architecture
DC brushless motor at 120 W input / 100 W output. Twice the input power of the OS-20L (60 W) — required to deliver the 60 Ncm maximum torque against the 50,000 mPa·s viscosity ceiling. No brush wear; designed for daily institutional duty.
60 Ncm maximum torque. 50% higher than the OS-20L's 40 Ncm. Combined with the higher-power motor, this is what extends the viscosity ceiling from 10,000 to 50,000 mPa·s.
Microprocessor-controlled speed regulation. Speed and run time set + monitored via the LCD; the microprocessor maintains set speed under variable load — important for the workflows that drove the OS-40L's spec (rising viscosity through the mix cycle as ingredients are added).
Sensor-based shutdown protection. Same protection as the OS-20L — if the propeller hits a high-viscosity blockage or mechanical obstruction, the drive shuts down before motor damage. The higher torque rating means the protection threshold is higher; the OS-40L can keep running under loads that would shut down the OS-20L.
Splash cover protects the connection mechanism from corrosion — important for personal-care, pharmaceutical, and food workflows where reagent overspray would otherwise reach the chuck/motor connection.
Feed-through chuck for accessory shafts. Tool-less tightening / loosening for fast accessory swaps. Same chuck design as the OS-20L — so the same propeller / paddle accessory line interchanges between the two stirrers.
Complete stand assembly included. Stand + mounting hardware secures the head to the stand for vessels up to 24 inches tall. Same chassis bundling as the OS-20L.
LCD control panel. Speed, run time, and operating mode displayed; programming via panel buttons.
Frequently Asked Questions
What viscosity can the OS-40L handle? Up to 50,000 mPa·s in a 40 L water-equivalent vessel — a 5× step-up over the OS-20L's 10,000 mPa·s ceiling.
What is the maximum torque and speed range? 60 Ncm maximum torque across a 30–2,200 rpm speed range, driven by a 120 W-input / 100 W-output DC brushless motor.
What comes included? The OS-40L mixer head, a complete stand assembly with mounting hardware, and a 4-arm stainless steel propeller (IPS2050-P-S4).
What size vessel does it accommodate? Vessels up to 24 inches tall, at capacities up to 40 L water-equivalent.
How is the motor protected against overload? Sensor-based shutdown stops the drive if the propeller hits a high-viscosity blockage or obstruction before the motor is damaged.
Ordering & Configuration
Standard configuration. The IPS2050-40 ships as a complete operating setup: the OS-40L mixer head (120 W DC brushless, 60 Ncm torque, 30–2,200 rpm), a complete stand assembly with mounting hardware, a 4-arm stainless steel propeller (IPS2050-P-S4), an LCD control panel, a 100–240 V US power cord, and the operator's manual.
Optional propellers and paddles (sold separately, shared catalog with OS-20L):
- IPS2050-P-S1 / -S2 / -S3 / -S4 — Stainless steel propellers (4 styles)
- IPS2050-P-T1 / -T2 / -T3 / -T4 — Teflon propellers for aggressive-solvent compatibility
Voltage variants. This SKU is the US-plug configuration; 115 V or 230 V is available by special order.
Family alternative. The IPS2050-20 OS-20L (20 L capacity, 10,000 mPa·s viscosity ceiling, 40 Ncm torque, 60 W input) is the lower price point for low-viscosity or smaller-volume work.
Use the quote request to specify: voltage and plug type, propeller / paddle accessory selection per intended sample chemistry, vessel size and height (confirms 24" max compatibility), training, and lead time.
Warranty: Manufacturer's standard Benchmark Industrial warranty applies.
OS-40L vs OS-20L selection: if your formulation work involves viscosities above 10,000 mPa·s (pastes, semi-solids, high-solids slurries) or vessels above 20 L water-equivalent, the OS-40L is the right spec. If you can stay below 10,000 mPa·s in 20 L vessels, the OS-20L lower price is sufficient. The torque-and-viscosity envelope is the operative selection axis.
