GRINO ROTAMIK SKS 475 2V vs Elektror 2SD720-50/5,5 Comparison

Both are 5.5kW two-stage side channel blowers (senza olio) with identical operating point: -470 mbar, 312 m³/h. They can replace each other, but there are significant differences in brand, internal structural details, motori, housings, performance curves and spare parts supply.

1. Informazioni di base

GRINO ROTAMIK SKS 475 2V PDF: Spanish brand, SKS series. 2V = 2-stage; 5.5kW; operating condition: 312 m³/h @ -470 mbar; maximum vacuum -500 mbar

Elektror 2SD720-50/5,5 PDF: German Elektror. 2SD = two-stage side channel; 5.5kW; operating condition approx. 312 m³/h @ -470 mbar; ultimate vacuum up to -500 mbar

1. Differenze fondamentali
2. Marca & Origine

SKS475 2V: Griño Rotamik from Spain, mid-range European side channel pump. Widely used in vacuum handling and pneumatic conveying, but limited agent network within China.

2SD720-50/5.5: German Elektror, premium side channel blower. Extensively adopted for industrial equipment and OEM applications, with mature spare parts support in China.

2. Girante & Flow Path Structure

SKS475 2V: Two-stage back-to-back impeller layout. Split aluminium housing with closed-type impeller blades. Single-stage variant SKS475 (without 2V suffix) has free air flow up to 552 m³/h.

2SD720-50/5.5: Two-stage side channel chambers arranged in series. Open impeller design with robust one-piece cast housing. Larger models in the 2SD series can reach ultimate vacuum up to -750 mbar.

3. Motor Specifications

SKS475 2V: IE2 motor, IP54, Isolamento in classe F. Built-in thermal protection as standard; silencer supplied separately (not factory fitted).

2SD720-50/5,5: Motore IE3 ad alta efficienza, IP54, Isolamento in classe F. Integrated inlet/outlet silencers. Factory fitted motor winding temperature sensor for direct PLC thermal protection signal connection.

4. Rumore & Peso

SKS475 2V: 74~78 dB(UN), ca. 72 kg

2SD720-50/5.5: 71~76 dB(UN), heavier with thicker housing, better low-frequency noise attenuation.

5. Performance Curve Characteristics (Chiave per la selezione)

SKS475 2V: Steep curve within -400 ~ -480 mbar. Flow drops sharply once vacuum exceeds -480 mbar. Suitable for stable vacuum conditions; not recommended for prolonged operation near ultimate vacuum.

2SD720-50/5.5: Gentle performance curve with higher overload margin. Stable under short-term vacuum spikes and pressure fluctuations; permits temporary operation close to ultimate vacuum.

6. Montaggio & Connection Dimensions

SKS475 2V: DN65 (2.5″) inlet/outlet. Spanish standard base mounting holes, incompatible with Elektror. Direct in-situ replacement requires base and pipework modification.

2SD720-50/5.5: DN65 inlet/outlet with different flange thread specification. German standard base footprint, not interchangeable with SKS475 2V.

7. Manutenzione & Pezzi di ricambio

SKS475 2V: Limited local stock in China, long lead times. Bearings, impellers and components require import ordering.

2SD720-50/5,5: Local agents stock common wear parts (cuscinetti, seals, filtri, silencer inserts) with faster after-sales response.

8. Fascia di prezzo

Procurement cost of SKS475 2V is generally lower than Elektror 2SD720-50/5,5.

III. Application Selection Guidance

✅ Choose SKS475 2V

Priorità di bilancio; stable vacuum without frequent spikes near ultimate vacuum; equipment exported to Spain / Southern Europe; existing plant using GRINO with established spare part system.

✅ Choose 2SD720-50/5.5

Large vacuum fluctuations, frequent start-stop cycles; stricter noise requirements; on-site service and fast spare parts required in China; continuous 24-hour operation; IE3 high-efficiency motor required plus PLC integrated winding temperature protection.

1. Caratteristiche comuni

Both are oil-free dry-running side channel blowers, no oil lubrication required.

Suitable for vacuum gripping, vacuum handling and powder conveying.

Both support variable frequency speed regulation.

Medium must be clean dry air; inlet filter is mandatory.

1. Replacement Risk Warning

Even though the operating point parameters fully match (312 m³/h @ -470 mbar), base mounting holes and nozzle flanges are not interchangeable. New base plate and pipe adapters must be fabricated for replacement.

GRINO ROTAMIK SKS 475 2V vs Elektror 2SD720-50/5,5 Outline Dimension Table

Unità: mm, DN65 connection, 5.5kW two-stage side channel blower

Key Mounting Replacement Notes

1. Pipe nozzles: DN65 nominal diameter for both, custom adapter required to convert external thread to flange connection;
2. Base plate: Mismatched centre height and foot print. Reuse of original base is impossible; new steel base or frame modification required;
3. Space clearance: 2SD720 is longer and taller. Verify internal equipment clearance to avoid mechanical interference;
4. Pipework: SKS475 2V has no built-in silencer. After switching to 2SD720, remove old external silencer to reduce line pressure loss.

GRINO SKS475 2V → Elektror 2SD720-50/5,5 On-site Retrofit Checklist

Applicazione: Replace existing SKS475 2V with 2SD720-50/5,5; 5.5kW two-stage vacuum side channel blower, working point -470 mbar, 312 m³/h

1. Installation Space Verification

Lunghezza totale: Old SKS475 2V ≈615 mm; new 2SD720≈650 mm, +35 mm longer. Check interference at motor rear side

Overall height: Old ≈430 mm; new ≈445 mm, +15 mm taller. Check clearance above for pipework/guard/cable clash

Overall width: Old ≈370 mm; new ≈385 mm, +15 mm wider. Confirm side maintenance access

Lifting space: New unit 7 kg heavier (79 kg). Verify lifting point and hoist capacity

Maintenance access: Terminal box on motor top. Confirm space for wiring and PT100 connector access

1. Base & Foundation Modification

Centre height difference: Vecchio 220 mm vs new 230 mm (+10 mm). Two options: add shim plates or fabricate new base

Foot hole pitch: Old 420×260 vs new 445×275. Original base cannot be reused

Base plate material: minimo. 10 mm steel plate with anti-corrosion coating; levelling shims recommended

Foundation bolts: Both M12. Check plate strength and anchor bolt capacity; rubber anti-vibration pads recommended to reduce vibration transmission

Controllo del livello: Level blower after installation to prevent impeller rubbing and premature bearing failure

III. Pipework & Nozzle Retrofit (DN65)

Tipo di connessione: SKS 2.5″ male thread vs 2SD720 flange thread, custom transition adapter required

Pipe routing: New blower has integrated silencers. Remove old external silencer to shorten piping and reduce pressure drop

Filtro: Reuse existing inlet filter, verify DN65 fit, replace all gaskets

Non-return valve / vacuum gauge: Retain mounting location, check adapter sealing. Air leakage directly reduces vacuum level

Flexible bellows: Flexible vibration isolators must be fitted at both inlet and outlet to isolate vibration; prevent pipe stress loading on blower casing

Pipe supports: Pipe weight must not rest on blower ports. Independent pipe supports required

1. Electrical Modification

Motor rating: Both 5.5kW with similar rated current. Existing circuit breaker and contactor are theoretically usable, but recheck rating

Motor insulation / protezione: SKS IE2; 2SD720 IE3 with built-in PT100 winding temperature sensor

Temperature wiring: Add PT100 signal cable to PLC / modulo di temperatura; configure high-temperature alarm and trip logic

Terminal box location: New terminal box on motor top. Redesign cable routing, check cable length to avoid tension

Cable sizing: Existing ≥4 mm² copper power cable can be reused. Verify terminals and reliable PE protective earth connection

VFD (se montato):

Re-enter motor nameplate parameters into VFD (corrente nominale, velocità, energia)

Adjust carrier frequency to reduce motor noise

Set overload and stall protection

1. Vacuum Control & Process Protection

Operating point: Target -470 mbar @312 m³/h. New model has flatter curve with improved vacuum fluctuation performance

Vacuum transmitter: Reuse existing sensor, re-calibrate zero point

Interlock logic review:

Low vacuum alarm (leakage protection)

Over-limit vacuum protection (anti-overload)

Motor high temperature alarm and shutdown

Sequence control: Open inlet valve → start blower; stop blower only after pressure relief to avoid vacuum shock

1. Pre-commissioning Inspection

Manual turning: Rotate impeller with power disconnected. No binding or rubbing noise

Elementi di fissaggio: Tighten base and pipe fittings to specified torque

Sigilli: Replace all gaskets, apply suitable sealant to threads/flanges

Filter inspection: Check filter element; replace if contaminated

Messa a terra: Confirm reliable protective earth connection

No-load trial run: Bypassare / release load, run 3~5 minutes. Check noise, temperature rise and vibration

VII. Commissioning Acceptance Tests

Measure no-load current, compare against motor nameplate

Close loop, adjust to target operating point: -470 mbar, record actual flow rate

Vibration measurement: Record housing vibration values against acceptance criteria

Noise inspection: Confirm no abnormal sharp noise

Temperature rise: Continuous run 1~2 hours, monitor winding temperature

Leakage test: Pressure hold test, confirm zero pipe air leakage

VIII. Pezzi di ricambio & Maintenance Update

Update spare parts list to Elektror OEM bearings, seals and silencer inserts

Intervallo di manutenzione: Both oil-free dry type. Regular inlet filter cleaning; bearing service life approx. 20000 H

Alarm system: Add PT100 high temperature alarm and HMI alarm message

⚠️ High Risk Reminders

1. Air leakage in vacuum system is the most common fault. All joint sealing must be carefully inspected, otherwise target -470 mbar cannot be achieved;
2. Do not rigidly couple pipework. Flexible joints are mandatory; pipe stress can crack blower housing;
3. Do not simply enlarge original base holes for fitting. Long-term vibration will shorten bearing life;
4. If original external silencer is not removed after retrofit, extra pressure loss will reduce flow performance.
5. Elektror 2SD Two-Stage Side Channel Blower Series (2SD720-50/5,5 belongs to this series)

Naming rule: 2SD frame size 50 / potenza del motore; 2SD = two-stage, 50 = 50Hz, power in kW. All models with integrated silencer + PT100 motor temperature sensor, oil-free dry-running, ultimate vacuum up to -750 mbar for larger frames.

Full Frame List

1. 2SD220 (small frame)

2SD220-50/0,55

2SD220-50/0,75

2SD220-50/1,1

2SD220-50/1,5

2SD220-50/2,2

2. 2SD320

2SD320-50/1,5

2SD320-50/2,2

2SD320-50/3,0

2SD320-50/4,0

3. 2SD520

2SD520-50/2,2

2SD520-50/3,0

2SD520-50/4,0

2SD520-50/5,5

2SD520-50/7,5

4. 2SD720 (replacement model for this project)

2SD720-50/4,0

2SD720-50/5,5 (target model)

2SD720-50/7,5

5. 2SD740 (alternative frame with same power)

2SD740-50/4,0

2SD740-50/5,5

2SD740-50/7,5

6. 2SD820

2SD820-50/7,5

2SD820-50/11,0

2SD820-50/15,0

7. 2SD840

2SD840-50/8,5

2SD840-50/11,0

2SD840-50/15,0

8. 2SD920 (largest frame)

2SD920-50/11,0

2SD920-50/16,5

2SD920-50/20,0

2SD920-50/25,0

Nota: 60Hz versions available (sostituire 50 con 60 for overseas projects). All models VFD compatible. Same frame size shares identical chamber/impeller; only motor differs for different power ratings.

1. GRINO ROTAMIK SKS Series (Original SKS475 2V belongs to this series)

SKS: side channel vortex pump; 2V = Two-Stage. Suffix without 2V = single-stage SKH/SKS; T1.B for 400V three-phase version

SKS Two-Stage (2V) Elenco dei modelli

SKS80 2V

SKS156 2V

SKS250 2V

SKS370 2V

SKS475 2V (existing equipment)

SKS570 2V

SKS750 2V

SKS Single-Stage Models (SKH / SKS, max vacuum approx. -400 mbar, insufficient for -470 mbar)

SKS80

SKS140

SKS156

SKS250

SKS370

SKS475 (single stage, no 2V suffix, not a valid replacement for two-stage unit)

SKS570

SKS750

III. Guida alla selezione rapida

1. Elektror 2SD: All 2SD models are two-stage, suitable for high vacuum >450 mbar absolute vacuum. Single-stage Elektror models designated SD/1SD, do not mix up.
2. GRINO SKS: Must carry suffix 2V for two-stage version. Models without 2V are single-stage with insufficient vacuum for -470 mbar application.
3. Operating Point Quick Reference (Your Working Condition)

Original unit: SKS475 2V, 5.5kW, 312 m³/h @ -470 mbar

Matching Elektror model: 2SD720-50/5,5; alternative option: 2SD740-50/5,5 (slightly different performance curve)