Defence Research & Development Organisation Interview Questions and Answers

Suction pressure, discharge pressure, and NPSH in pumps are calculated using specific formulas and measurements.

• Suction pressure is calculated by measuring the pressure at the pump inlet.

• Discharge pressure is calculated by measuring the pressure at the pump outlet.

• NPSH (Net Positive Suction Head) is calculated by subtracting the vapor pressure of the fluid from the total suction head.

• Formulas: NPSH = (P_atm - P_vap) / (rho * g) + h_suction, where P_atm is atmospheric pressure...read more

I would investigate the root cause of the two phase flow and take appropriate corrective actions.

• Check for any blockages or restrictions in the control valve

• Verify if the control valve is properly sized for the flow conditions

• Consider adjusting the pressure or temperature to prevent two phase flow

• Consult with other engineers or experts for further analysis

• Implement changes to the control system if necessary

Pumps are selected based on the required flow rate, head, type of fluid, operating conditions, and budget.

• Consider the required flow rate and head for the application

• Select a pump type suitable for the fluid being pumped (e.g. centrifugal pump for water)

• Take into account the operating conditions such as temperature and pressure

• Evaluate the budget constraints and choose a pump that meets the requirements within budget

Mac ab theile Method is used for column sizing in chemical engineering.

• Mac ab theile Method is an empirical method used to size distillation columns based on the number of theoretical stages required for separation.

• It involves calculating the minimum reflux ratio required for separation and then determining the number of theoretical stages based on the operating line and equilibrium curve.

• The method takes into account the feed conditions, product specifications, and the type ...read more

CV for a control valve can be calculated using the formula: CV = Q / (SG * sqrt(ΔP))

• CV is the flow coefficient of the valve

• Q is the flow rate in gallons per minute (GPM)

• SG is the specific gravity of the fluid

• ΔP is the pressure drop across the valve

PSV sizing is the process of determining the required size of pressure safety valves to protect equipment from overpressure.

• PSV sizing involves calculating the relieving capacity required to protect equipment from overpressure events.

• Factors such as maximum allowable working pressure, design pressure, and relieving pressure are considered in PSV sizing.

• Codes and standards such as API 520 and API 521 provide guidelines for PSV sizing calculations.

• PSV sizing may involve determi...read more

P&ID includes symbols and diagrams that represent the process flow, equipment, piping, instrumentation, and control systems in a plant.

• Symbols representing equipment such as pumps, valves, tanks, and vessels

• Lines representing piping connecting the equipment

• Instrumentation symbols for sensors, transmitters, and control loops

• Control system symbols for controllers, PLCs, and HMI panels

• Annotations for labeling and identifying components