Vibration, dynamics and noise

formerly BETA Machinery Analysis and SVT Engineering Consultants

Menu

Surge Sensitivity Calculator

Inertia number evaluation – a simplified method to calculate surge sensitivity

This free calculation tool can determine your compressor application's risk of surge. It provides a quantitative score using the non-dimensional inertia number to determine the optimal level of surge analysis given the compressor’s proclivity to surge.

Please input your values below:

Name Value Unit Explanation and Assumptions
Rotor Max Speed rpm Max speed possible for compressor
Max Head at Surge kJ/kg Max head at surge line
Max Mass Flow at Surge kg /sec Max mass flow on surge line
# of Wheels on Drive Train  
Type of Drive
Effective Speed rpm
Inertia: Calculated Value kg-m2
or Inertia: User Input kg-m2 * User may input inertia directly or program will calculate it based on regression fit and N, type of drive, and wheel count.
Inertia Value for Model kg-m2
Piping Length in Recycle Loop ft
Speed of Sound ft/sec SOS for gas mixtures in ft /sec
  • Light nat gas, SG = 0.6, SOS = 1350
  • Heavy gas mix, SG = 0.85, SOS = 1000
  • Pure CO2, SOS = 800
  • Pure nitrogen, SOS = 1150
  • Pure ethylene, SOS = 950
Tau - Time Delay sec *Assume 0.15 sec valve time delay

Ni, Inertia Number

Surge sensitivity inertia number risk evaluation

Summary: Wood Group VDN Service Offering

Level 1 – Surge Sensitivity Calculator – FREE, helps to answer these  questions?

  • Overall risk of your installation to surge?
  • Elaborate on the experience with designs?
  • Complications of multiple units, multiple modes of operation?

Level 2 – Helps to determine:

  • Optimal valve size (cold recycle, and hot recycle if needed)
  • Specifies necessary valve response time
  • Better assessment of risk (impedance line slope)
  • Qualitative assessment of installation risks, (ie. need for hot recycle, dynamic study)
  • Fast, can often turn around in less than a week (provided information is available

Contact us for inquiries, technical support, and pricing for a Level 2 analysis.

Level 3 – Accurate assessment of real surge behavior

  • Uses the most accurate surge modeling available to test the surge control system performance
  • Models the actual piping layout, valves, and components
  • Identifies dangerous operating scenarios
  • Recommends detailed design improvements
  • The most comprehensive assessment of surge risk, with solutions to mitigate risks

Please contact us for Level 3 inquiries.

Related Information and Services

Free webinar

Webinar

Learn how fixing common reliability and integrity problems can help you navigate current industry challenges while increasing cash flow in your facility.
Register now