SES420 - Vacuum Systems
Vacuum Systems

The SES420 transformer dry-out vacuum systems are available as standalone skids, cargo trailer mounted, or integrated into an SES320 oil processor.

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The SES420 family of vacuum packages are targeted at transformer dry out applications but can be custom engineered for other industrial applications on request. The SES420 series is packaged in four standard size ranges ( 375,700,1200,1650 CFM) with backing vacuum pump type, booster bypass, and VFD atmospheric startup options. These systems are available as stand-alone skids, stand-alone cargo trailer packages, and SES320 oil processor integrated. 


SES420 Highlights

Two Stage Systems

Direct Drive Booster Pumps  

  375, 700, 1200, 1650 CFM Standard Flow Ranges 

Dry Screw, Two Stage Piston, Rotary Vane Backing Pump Options

VFD Atmospheric Booster Start and Internal Bypass Booster Options




SES420 cutout 500x500 min


  • Oil Sealed Rotary Vane
    •  SES420-1650 / SES420-1200 / SES420-700 / SES420-375
      Vane pumps are the least expensive option and require the most maintenance time and cost. The single stage vane pump supported packages have a slightly high ultimate vacuum than the screw and piston supported pumps.   
  • Single Stage Oil Sealed Rotary Piston 
    • SES420-1650 / SES420-1200 / SES420-700 / SES420-375
      Piston pumps are time proven, more robust than vane pumps, and less expensive to repair than screw pumps.  Air cooled pumps are available in the SES420-275 & SES420-700 sizes.  In the larger sizes the piston pumps are liquid cooled and  come with an air cooled closed loop cooling ciruit. 
  • Two Stage Oil Sealed Rotary Piston 
    • SES420-1650 / SES420-1200 / SES420-700 / SES420-375
      When using vane or single stage piston pumps performanace is affected by seal oil quality. Two-stage piston pump design eliminates this problem, providing consistent performance even when operated with seal oil containing large amounts of water contamination. The ultimate performance and throughput will be slightly less than an equivalent screw pump supported package.
  • Dry Compression Rotary Screw 
    • SES420-1650 / SES420-1200 / SES420-700 / SES420-375
      Dry screw pump supported systems will provide the lowest ultimate vacuum pressures, as well as the highest throughputs, and do it consistently whenever the pump is turned on.  There is no seal oil to degrade and affect pump performance.  No seal oil means no routine oil changes. Maintenance time and related cost is a fraction of what a piston or vane pumps costs to maintain.  The dry screw pumps are also among the most expensive backing pump option to purchase and repair.  The SES40-375 dry screw option is a single stage system.   

  • Non-Bypass Vacuum Booster  
    • SES420-1650 / SES420-1200 / SES420-700 / SES420-375
      Standard is an Aerzen direct drive Roots-style rotary lobe booster w/o an internal bypass valve.  A pressure cutin switch is provided.  Cutin pressures will range between 10 - 15 torr depending on the package size and backing pump selected. 
  • Optional VFD Controlled Vacuum Booster 
    • SES420-1650 / SES420-1200 / SES420-700 / SES420-375
      VFD control is added to the standard Aerzen direct drive Roots-style rotary lobe booster.  Atmospheric startup is provided.  A pressure cutin switch is not required. The booster will be utilized at a reduced speed through the entire pump down range.  Transformer pump down times will be reduced by about 20%.
    Optional Bypass Vacuum Booster
    • SES420-1200 / SES420-700
       An optional Leybold direct drive Roots-style rotary lobe booster with an internal bypass valve is available.  The bypass valves closes at 35 torr.  A pressure cutin switch is provided to eliminate valve high-pressure range.  Cutin pressure will be 35 torr.

  • SES420 Standard Features
    • Safety booster pump discharge high temperature shut down interlock
    • Panel mounted digital  full scale vacuum gauge 
    • NEMA 4 control panel w/ PLC logic
    • No Fuses -100% Circuit breaker protected 
  • Available System Options
    • Safety oil trap w/ high level shut down interlock
    • Panel mounted remote vacuum gauge w/ 200' cable
    •  An automatic vacuum shut-off valve w/ pneumatic spring return actuator
    • Vacuum line dew point monitor
    • Vacuum line cold trap

The SES420 can be stand-alone skid-mounted, packaged in an easy-to-tow cargo trailer, or integrated into a SES320 Conditioning System or a SES441 Filtration system.   

SES420   GP Site 400 x 175





  • Skid Mounting
    Built-to-order skid-mounted equipment can normally be built to meet customer footprint and access requirements.  Consult SESCO with special requests.
  • Cargo Trailer Mounting
    All cargo trailers are specifically engineered to accommodate equipment load, weight distribution, to provide optimum towing conditions. Cargo trailer weight capacities (GVRW) range from 4,000 to 16,000 Lbs. SESCO will provide the cargo trailer size and weight capacity options available for the system being quoted.