Roots Blowers

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Operation

The SRT blower has a pair of tri-lobular rotors, with conjugate profiles turning in opposite directions inside a suitably formed casing, imprison the air or gases in the chambers formed between the rotor and the casing. The air or gas will be conducted towards the discharge of the machine, where the displaced air or gas is pressurized by the resistances and will find a backpressure that will help to automatically adjust the pressure to that found in the system itself.

The greater rigidity of the tri-lobular rotor, the better distribution of pressure around each lobule, the reduction of pressure peaks caused by backflow of the gases in the chambers formed between the lobules and the blower casing enable the machine to operate with a pulse cycle 30% below that of the bi-lobular rotor, improving the uniformity of the flow.

The synchronous operation of the lobules is obtained by means of a pair of high precision machined synchronized gears. The increased frequency with which the cycle repeats itself also improves the mechanical performance, consequently reducing the machine’s vibration and noise generation, on average around 5 dBA.

Applications

  • Pneumatic transportation of bulk materials: In vacuum or pressure, with wide application in the transportation of ashes, cement, flours, crystals, grain, pellets, sawdust, unloading of ship holds, trucks, among others.
  • Aeration of tanks, ponds, reservoirs: In treatment of effluents.
  • Washing of filters: In backpressure in the treatment of effluents.
  • In steelmaking: In furnace air blowing at direct reduction plants.
  • In high-vacuum processes: Operating as a primary pump. Requires special seals.
  • In pressure boosting processes: As a booster, supplied to resist inlet pressures of up to 2,5 bar.
  • In transportation of gases in general: With applications in the chemical, petrochemical and metallurgical industries, with special seals and materials, such as stainless steels, super alloys.
  • In treatment of waste: Blowers are used in sanitary landfills to pump the gases produced by the decomposing material. In addition they are used in the recovery of sub-soils in soils degraded by pollutant agents.
  • Cleaning: in mobile units destined for cleaning large areas by aspiration and for pulverization of granulates and powdered products in large areas.

Advantages

Oil-free air

The pumping chamber within which the lobules transport the air from suction to discharge, is sealed by means of an oil deflector disc, operating together with seals that prevent the oil vapors to penetrate the pumping chamber.

Shaft/tri-lobular lobule assembly

The tri-lobular lobules and shaft constitute a more rigid assembly than the bi-lobular lobules, and a better distribution of pressure around the lobule. It results in lower radial loads, reducing the bearing loads, increasing their service life, enabling the machines to operate with less vibrations and higher speeds, allowing adoption of smaller machines and reducing installation cost.

Pulsation and vibration

The pumping chambers are fitted with pulsation and noise reducers. In addition, the tri-lobular lobules generate a pulse/noise frequency higher than the bilobular, which enables better efficiency in dampening pulsations/noise.

No-leak lubrication

Lubrication of the gears and bearings is done by splashing, by means of splashing rings in an oil bath. Sealing of the exit shaft is done by means of labyrinth type seals which, contrary to the normal rubber retainers, have no contact with the shaft. The system eliminates oils leaks, reducing downtime for maintenance.

Precision machining

Manufactured in high precision CNC machines, specifically done for this service, which permit the precision of the components, essential for the machine to have high volumetric efficiency, guarantee of good performance within its specifications.

Insensibility

System non susceptible to impurities such as solid or liquid particles and can operate continuously with water injection to cool the gas or clean the pumping chamber.

Lubrication

Gears and bearings are splash lubricated and possibility of installation of cooling finned tubes to reduce the oil temperature in extreme operation conditions (only when mineral oils are used; not necessary if specified synthetic oils are used).

Lobes

Entire shaft of special alloy steel and lobes of high quality cast iron guarantee the extreme rigidity of the unit.

Casing

In one unique piece of high quality cast iron for high resistance and long life operation.

Sealing between gas pumped and atmosphere

Specially studied to reduce air leak and not allow lubricating oil in the casing.

Long life bearings

Calculated for 100,000 hours operation working at maximum specified conditions.

Characteristics

  • Capacity: from 70 m3/h to 25.000 m3/h.
  • Pressure (as blower): up to 1,000 mbar (approx.. 10 mwc)./li>
  • Vacuum: down to 500 mbar.
  • Vacuum: down to 900 mbar, only for VF type machines (with partial air admission).

Maximum pressure sustained:

  • Maximum pressure: 2,5 bar.
  • Nodular cast iron casing: permits pressures up to 5,0 bar.
  • Pressures above 5,0 bar subject to future consultation.

Materials

  • Casings: In high-quality ASTM A48 CL.30 cast iron or in nodular cast iron.
  • Rotors:In ASTM A48.cl.30 cast iron in the other sizes.
  • Shafts: In high-resistance SAE 4340 steel.
  • Gears:In hardened and machined SAE 8620 steel.
  • Materials for special applications: For special applications to pump corrosive gases, steam among others the compressors may be supplied in special alloys, suitable for each operating condition, subject to future consultation.

Construction Variations

Exit shafts sealing

Different types of seals are used, depending on the process conditions.

Oil/air sealing

Besides the labyrinths normally used, specific seals for the process can be applied, among which, double mechanical seals, graphite labyrinths, special gaskets, etc.

VF version:

Vacuum in a normal blower is limited to 500 mbar, since beyond this limit, due to the reduction of the volume of fresh air by aspiration, the machine begins to heat up to temperatures not tolerated by it. To avoid this inconvenience, machines that inject fresh air in the space delimited by two rotors (under vacuum) are used, and the cooling caused by the input of cold outside air does not permit excessive temperature increase, enabling the machine to operate down to a maximum vacuum of 900 mbar (see below operating scheme):

Performance

The data refers to inlet with air at 20ºC and 1,000 mbar abs pressure.

Blower Model 710 713 720 816 821 831 1019 1027 1039
Maximum Capacity m3/min 3,85 6,10 8,90 9 11,23 18,31 17,70 23,33 32
Maximum Pressure mbar 900 1000 700 1000 900 700 1000 1000 700
Maximum Speed rpm 4800 4800 4800 4800 4800 4800 4800 4800 4800
Shaft Power kW 8,50 11,85 12,8 14,91 23,15 20 25 50 48
Drive Power kW 11 15 15 25 30 25 30 55 55
Noise Pressure Level
(with or without sound proof cabine)
dBA 94 / 72 95 / 74 96 / 77 98 / 78 98 / 78 102 / 80 103 / 82 104 / 84 104 / 80
Max. Discharge Temperature ax. ªC 132 140 95 125 132 116 127 132 112
Weight kgf 67 77 92 105 120 140 165 190 214
Lenght mm 463 497 564 573 629 728 668 748 861
Width mm 319 319 319 355 355 355 355 420 420
Height mm 267 267 267 317 317 317 317 317 317
Flanges Nom. Diameter mm 80 80 80 80 100 100 199 100 150
Blower Model 1323 1334 1348 1632 1643 1661 2138 2151 2172
Maximum Capacity m3/min 29 38 55 45 60 85 65 93 135
Maximum Pressure mbar 1000 1000 700 1000 1000 700 1000 800 600
Maximum Speed rpm 3800 3800 3800 3000 3000 3000 2400 2400 2400
Shaft Power kW 31,41 78 80 113 117 119 135 150 160
Drive Power kW 40 90 90 132 132 132 150 175 185
Noiser Pressure Level
(with and without sound prof cabine)
dBA 106 / 86 106 / 87 104 / 86 107 / 88 104 / 86 107 / 87 106 / 84 106 / 86 106 / 85
Max. Discharge Temperature ax. ªC 127 130 98 121 117 86 100 112 76
Weight kgf 304 330 380 395 452 555 740 780 870
Lenght mm 764 874 1014 888 1000 1180 1070 1166 1376
Width mm 579 579 579 704 704 704 740 740 740
Height mm 398 398 398 498 498 498 628 628 628
Flanges Nom. Diameter mm 150 150 200 200 200 200 200 250 250
Blower Mode 2745 2767 2780 3362 3384 33113 4289 42110
Maximum Capacity m3/min 102 160 230 160 212 282 360 415
Maximum Pressure mbar 1000 800 600 1000 800 600 1000 600
Maximum Speed rpm 2000 2000 2000 1600 1600 1600 1200 1200
Shaft Power kW 154 247 287 317 331 361 387 475
Drive Power kW 185 300 330          
Noise Pressure Level
(with and without sound prof cabine)
dBA 107 / 88 106 / 90 105 / 86 106 / 87 106 / 87 106 / 86 107 / 85 107 / 88
Max. Discharge Temperature ax. ªC 130 123 75 130 96 75 10 86
Weight kgf 1200 1440 1630 2200 2620 2700 2600 2800
Lenght mm 1223 1452 1662 1564 1811 2049 1680 2026
Width mm 880 880 880 958 958 958 971 971
Height mm 710 710 710 990 990 990 971 1120
Flanges Nom Diameter mm 250 300 350 300 350 400 500 500

Accessories

OMEL supplies a whole range of accessories or peripherals able to put the unit into operating conditions within the current legislation. Motors, bases, aspiration and discharge silencers, absorption or resonance, inlet filters, couplings, safety and retention valves, de-noise cabins, and flexible joints are some of the accessories normally supplied.

Main Dimensions (vertical suction and discharge)

OMEL - Roots Blowers - Vertical and Horizontal

For the table of dimentions of SRT Product Line please refer to product catalog.

Attention: the blowers sizes SRT 07 to SRT 10 are also manufactured with horizontal fittings, and then they will be called SRTH followed of the size.

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