Emergency Vent Cover

→ Emergency relief valve open to greatly increase the venting capacity of petroleum storage tanks when the internal pressure rises above the set point. it remains closed tightly when internal pressure below the settings.

VALVE OPERATION & SIZING CALCULATION

A. Valve operation

Emergency relief valve is the safety valve to protect the storage tank from the inflation(pressure) with the function to discharge rapidly the overpressure developed during external fire around the storage tank or the Excessive fluid intake more than the capacity of pump planned.

Emergency relief valve is designed to be Cushioned air seating, Teflon (PTFE/FEP- 2 Layer) seating diaphragm are Standard. It minimize sticking caused by resinous vapors and atmospheric moisture. The Seat tightness is 75% of set point by API 2000. It is designed to be self closing under normal operation by Internal Guide & external Hinge and the restraining cable to Connect the Cover assembly and Flanges also serve a grounding cable.

The Emergency relief valve provides pressure / or vacuum relief when the tank is loading phenomena and external fire or Rupture cases also the pressure is above the setting (Operational Fixing pressure), the Emergency relief valve operate automatically to protect the storage tank from inflation.

The weight loaded type model max. set point is 70/-43mbarg and spring loaded type is till 900/-900 mbarg.

B. Valve Sizing

Where the fluid properties are similar to those of hexane, the required venting capacity can be determined as table 03.

If the height of the tank exceeds 9.14 meters, use the same number to the tank which is higher than 9.14 meters for calculation. If wetted surface area is wider than 260 m2, there are two cases. Refer to the following table 01.

Table 01

Where the fluid properties are other than hexane ,the required venting capacity can be calculated give by below equation.

q : is the heat input from the fire exposure as given by table 02 ,expressed in watts.

F : is the environmental factor from table 09 (API2000 clause 3.3.3.3.2).

L : is the latent heat of vaporization of the stored liquid at the relieving pressure and temperature ,expressed in J/kg.

T : is the absolute temperature of the relieving vapor ,expressed in kelvins.

M : is the relative molecular mass of the vapor.

Table 02

Table 03

The size of the valve shall be selected by comparing our certified flow / pressure drop diagrams with calculated inbreathing and out breathing.

Check point.

1) Set pressure: The adjusted pressure or vacuum which valve start to open.

2) Over pressure: Pressure increase at the valve inlet above the set pressure or vacuum.

3) Overpressure calculation

Example

– Valve set pressure = 100mm.W.C(90% or same as tank design pressure)

-Tank Design pressure = 100mmW.C

Max. allowable over pressure = 10% (Emergency relief valve set pressure is usually 90% or same as Tank design pressure hence max. allowable design pressure is 10% generally) Size select comparing flow/pressure drop diagram with calculated emergency out breathing.

Example (Check figure 01 & 02)

Calculated Out breathing = 19,910m3/hr

Valve set pressure = 100mmW.C

Calculated Max. allowable over pressure = 10%

WEIGHT LOADE TYPE

                           

                                                                                                            ATEX-KSEP

KSEP TYPE

According to API 2000 Code : The series KSEP is designed to provide emergency pressure relief for storage tanks when exposed to overpressures that are not handled by standard tank vents. These vents provide the capacity to meet API standard 2000 for emergency venting due to fire exposure when properly sized. These covers also provide quick easy access for tank inspection and maintenance.>>>>>Datasheet

                       

                                                                                                       ATEX-KSEPK

KSEPK TYPE

According to API 2000 Code : The series KSEPK is designed to provide emergency pressure relief for storage tanks when exposed to overpressures that are not handled by standard tank vents. These vents provide the capacity to meet API standard 2000 for emergency venting due to fire exposure when properly sized. These covers also provide quick easy access for tank inspection and maintenance.>>>>>Datasheet

 

                                 

                                                                                                          ATEX-KSEV

KSEV TYPE

According to API 2000 Code : The series KSEV is designed to provide emergency pressure vacuum relief for storage tanks when exposed to over pressures and over vacuum that are not handled by standard tank vents. These vents provide the capacity to meet API standard 2000 for emergency venting due to fire exposure when properly sized. These covers also provide quick easy access for tank inspection and maintenance. >>>>>Datasheet

 

SPRING LOADED TYPE

 

KSES TYPE

According to API 2000 Code : The series KSES is designed to provide emergency pressure relief for storage tanks when exposed to overpressures that are not handled by standard tank vents. These vents provide the capacity to meet API standard 2000 for emergency venting due to fire exposure when properly sized.>>>>>Datasheet

 

KSESV TYPE

According to API 2000 Code : The series KSESV is designed to provide emergency pressure vacuum relief for storage tanks when exposed to overpressures and overvacuum that are not handled by standard tank vents. These vents provide the capacity to meet API standard 2000 for emergency venting due to fire exposure when properly sized.>>>>>Datasheet