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)

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.