Surge Scientific · Model OHS-40D
Overhead Laboratory Stirrer
40 Liter · 40 N·cm Torque
Brushless DC Motor · 50–2000 RPM · 5,000 mPa·s Viscosity · ±1% Speed Accuracy · 110 W Output
The OHS-40D is the stirrer you reach for when the 20L benchtop unit runs out of motor — 40 liters of batch capacity, five times the viscosity rating, and nearly double the output power, all driven by the same closed-loop brushless DC controller that holds your setpoint regardless of what the sample does mid-run. Emulsions, polymer blends, viscous dispersions — the shaft keeps turning at the speed you set.
Why Viscosity Headroom Changes Everything
Most overhead stirrers quote their torque rating at water-thin viscosity — where any motor looks strong. The honest spec is the one buyers rarely check: what viscosity can the unit hold at setpoint? A stirrer rated for 1,000 mPa·s will visibly slow the moment your polymer crosslinks, your suspension thickens, or your emulsion inverts. The setpoint on the display becomes a number the motor aspires to, not a speed it delivers.
The OHS-40D carries a 5,000 mPa·s viscosity rating — five times the headroom of entry-level units — paired with 40 N·cm of torque at the shaft. That margin is what keeps a stirrer useful across the full evolution of a reaction, not just the easy first hour.
40 N·cm of Usable Torque
Rated for 40 liters at up to 5,000 mPa·s — the working range of polymer synthesis, resin blending, and high-solids formulation. Not a peak spec, a sustained one.
Brushless DC Drive
110 W max output power with zero brush wear. No carbon dust, no periodic service, no performance drift — a service life counted in years of duty, not motor hours.
Triple-Layer Safety
Proprietary torque-overload cutoff, independent over-temperature protection, and dedicated motor protection — with four audible fault codes for instant diagnosis.
±1% Speed Accuracy
Closed-loop control holds 50–2000 RPM in stepless 10 RPM steps. The display alternates set and actual speed so you see the controller working — not just trust it.
"40 N·cm held flat to 5,000 mPa·s." — The OHS-40D delivers its rated torque across the full viscosity curve. When your emulsion thickens or your resin cures, the controller pushes more current — the shaft doesn't slow down.
Key Features
- Max torque 40 N·cm at the shaft
- Max batch volume 40 L (water)
- Max viscosity 5,000 mPa·s
- Max output power 110 W
- Speed range 50–2000 RPM
- Stepless 10 RPM increment
- ±1% speed accuracy (closed loop)
- Bright LED display — set and actual speed alternating
- Maintenance-free brushless DC motor
- Through-shaft housing — adjustable impeller height
- 0.5–10 mm keyed clamping chuck
- Overload torque cutoff circuit
- Independent over-temperature protection
- Dedicated motor protection circuit
- Four fault codes with audible alarm
- Large knob — push to start / stop, turn to set speed
- IP42 dust and splash protection per DIN EN 60529
- Dual voltage: 100–240V, 50/60 Hz
- Compact 71 × 174 × 240 mm drive head
- 2.5 kg head weight — easy to reposition
Ideal Applications
Polymer & Resin
Polymerization, resin crosslinking, and high-solids blending where viscosity climbs sharply mid-reaction.
Formulation & Scale-Up
Cosmetic, personal-care, and coating formulations — pilot-scale batches that outgrow 20L gear but aren't yet reactor-scale.
Pilot & Process Labs
Dissolution, suspension, and emulsion work in pilot plants, process-development labs, and production-support QC.
What's in the Box
Every OHS-40D ships with the components needed to begin stirring — support stand, extension arm, chuck, and drive head. Impellers are sold separately to match your sample's viscosity and geometry.
Technical Specifications
| Parameter | Specification |
|---|---|
| Model / SKU | OHS-40D |
| Max Torque at Shaft | 40 N·cm |
| Max Stirring Quantity | 40 L (H₂O) |
| Max Viscosity | 5,000 mPa·s |
| Speed Range (Normal Load) | 0 / 50–2000 RPM |
| Speed Increment | Stepless, 10 RPM |
| Speed Accuracy | ±1% |
| Motor Type | Brushless DC, maintenance-free |
| Max Output Power | 110 W |
| Rated Power | 65 W |
| Display | LED — set / actual speed alternating |
| Clamping Chuck Range | 0.5–10 mm |
| Overload Protection | Yes |
| Motor Protection | Yes |
| Over-Temperature Protection | Yes |
| Ingress Protection | IP42 (per DIN EN 60529) |
| Permissible Ambient Temp | 5–40°C |
| Permissible Relative Humidity | ≤ 80% |
| Voltage / Frequency | 100–240V, 50/60 Hz |
| Dimensions (D × W × H) | 71 × 174 × 240 mm (without extension arm) |
| Weight | 2.5 kg (with extension arm and chuck) |
Surge Scientific Warranty & Support
This instrument is sold through Surge Scientific, your trusted laboratory equipment partner. Our product specialists are available Monday–Friday for assistance. The OHS-40D is backed by a 2-year all-inclusive manufacturer's warranty. Contact us at info@surgescientific.com or reach out directly to our support team at 855.943.3344 for pre-sales questions, impeller selection, quotes, and technical assistance.