RUVAC WS 251 3Ph 200/230/400 V 50 Hz, 200-208/265/460 V 60 Hz; Mineral oil LEYBONOL LVO 130

Leybold RUVAC WS 251 – Roots pump with canned motor and 253 m³/h nominal pumping speed

The RUVAC WS 251 is the smallest Roots pump in the WS series with canned motor. The rotor and stator winding are separated by a vacuum-tight can, so there is no shaft feedthrough to atmosphere – the integral leak rate is ≤ 1 × 10⁻⁴ mbar·l/s. As a WS version without pressure equalisation line, it is only switched on once the backing pump has reached the cut-in pressure; with a two-stage TRIVAC D 65 B as the backing pump, Leybold specifies an ultimate total pressure of < 8 × 10⁻⁴ mbar. The nominal pumping speed is 253 m³/h at 50 Hz and 304 m³/h at 60 Hz, the maximum effective pumping speed 210 and 251 m³/h respectively. The pump measures 694 × 250 × 300 mm, weighs 90 kg and is connected via DN 63 ISO-K; the noise level is below 63 dB(A).

Typical applications

The RUVAC WS/WSU work as boosters in front of an oil-sealed or dry backing pump. Leybold recommends the canned-motor series for applications requiring a high pumping speed between 10⁻² and 10⁻⁴ mbar, for processes in which neither air may enter nor pumped medium escape, and for the extraction or transfer of high-purity gases. Typical applications of the RUVAC series are heat treatment and furnace construction, metallurgy, large-area coating, load-lock chambers and crystal pulling systems for the semiconductor and solar industries.

Variants of the RUVAC WS 251

The RUVAC WS 251 is available from Ehrler & Beck in two variants (part numbers 11722, 11727). All variants have the same canned motor with a motor power of 1.1 kW at 50 Hz to 1.4 kW at 60 Hz for mains voltages from 200 V to 460 V. They differ mainly in the oil filling: mineral oil LEYBONOL LVO 130, PFPE LEYBONOL LVO 400.

Features of the RUVAC WS/WSU

• Air-cooled canned motor: no shaft feedthrough to atmosphere, integral leak rate ≤ 1 × 10⁻⁴ mbar·l/s
• Temperature monitoring in the motor's stator winding; separate fan under the fan cover
• Operation on 50 and 60 Hz mains; higher speeds are possible with a frequency converter
• All elastomer seals made of FPM (FKM)
• WSU: integrated pressure equalisation line with differential pressure valve as overload protection
• Supplied for vertical pumping direction; conversion to horizontal pumping direction possible by the customer
• Oil filling supplied separately; inlet flange with dirt trap, pump vented with nitrogen for corrosion protection

Pumping speed 50Hz	210
Pumping speed 60Hz	251
Ultimate pressure	8 × 10-4
Rated motor power 50Hz	1.1
Rated motor power 60Hz	1.4
Weight	90
Length	69.4
Width	25
Height	30
Inlet connection flange	DN 63 ISO-K
Outlet connection flange	DN 63 ISO-K
Noise level	63 dB(A)
Cooling method	Air cooling
Oil type	LEYBONOL LVO 130, LEYBONOL LVO 400

Additional technical data