Answers to Some FAQs
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Q1 What is a PD flow-meter and mass flow meter?
ANS :A Positive Displacement (PD) flow meter requires fluid to physically move rotary component inside a fixed casing, which is coupled with a pulse-generating unit. The number of pulses generated is related to the number of rotations of the component which in turn is calibrated to the volume of fluid flowing through the pipe. Mass flow meter (MFM) or inertial flow meter is a device that measures the mass of fluid flown past a particular point. In this device, fluid is made to pass through a twisted/curved tube which vibrates under the Coriolis effect. The numbers of vibrations give the mass flow rate. Since MFM doesn’t have rotary components, wear/tear is minimum, it is more consistent over long periods than PD flow-meter. Transactions between OMC’s are done by MFM.(watch related video for better understanding.)
Q2 How do you identify the different personnel working at a terminal?
ANS :They are identified on the basis of colour of safety caps worn by them.(See this:)
Q3 Explain the working of DBBV valve.
ANS : Double Block and Bleed Valve (DBBV) is a valve with two seating surfaces, which provides the blocks on both the upstream & downstream side of the valve. The obturator has a trapezoidal shaped port at its center to allow the fluid to pass through it when the port is along the flow. When the valve is in closed position, the port/cavity is perpendicular to the flow. This provides positive segregation (no bypass whatsoever) of upstream and downstream flow. This segregation can be checked bleeding the port and seeing if any further leakage can be observed in the cavity. Thus, DBBV has a great benefit over other valves by providing a means to check proper block has been achieved.(Watch this Video to understand better 🙂
Q4 Explain the working of ROSOV valve.
ANS : Remotely operated Shut-off Valves (ROSOV) is a fail-safe system that comprises pneumatic/ electrohydraulic actuator, and solenoid valves and accessories integrated on a control panel. IT has two pistons which work under pneumatic pressure supplied by pumps from the pump house. As it a quick shut-off valve, it is placed closest to the tank (body valve) to minimize any spillage/leakage. It is a ‘triple-offset butterfly valve’, which provides bi-directional bubble-tight sealing and thus is reliable in case of emergencies. It can be closed remotely but can only be opened manually. Apart from dealing with emergency scenarios, ROSOV also plays a crucial level in preventing overspill of tanks. Automatic Overspill Protection System (AOPS) is directly connected to ROSOV and in case the oil level reaches HHH, AOPS gets triggered which automatically closes ROSOV and prevent any overspill to occur.(Watch this video for better understanding:)
Q5 Why recirculation of product is required?
ANS :Recirculation of product in tank is required to maintain consistency of product under changing weather conditions. A series of recirculation pipes are connected to the tanks for the purpose of recirculation. Recirculation is also done to mix PCK (Pipeline Compatible Kerosene) in whole batch if received through Multi Product Pipeline. This is because PCK has more density and comes last through the pipeline.Q6 Why ethanol is generally stored in above ground horizontal tanks and not in vertical tanks?
ANS :As ethanol is a very volatile product, so it cannot be stored in a CRVT. And for FRVT there is a possibility of entering water into the tank. Ethanol has a very high affinity for water as it reacts with water and due to which some ethanol product gets converted into water. So, it needs to be protected from water.Q7 What is AOPS and how does it work?
ANS :AOPS is Automatic Overspill Protection System which has a tuning fork placed at HHH level. As product reached HHH level, due to change of medium around the fork its frequency changes. AOPS notices the change in frequency and shut off the ROSOV. AOPS is hardwired to ROSOV as it is last measure of safety during product receipt.Q8 What happens of product level in tank cross safe filling height?
ANS :Radar gauge will monitor the product level in the tank during receipt continuously. As product level cross safe filling height Radar Gauge will send alert to control room. If control room do not respond and product level reached HHH level, AOPS gets activated and it stops the receipt.Q9 Why opening of ROSOV is manual?
ANS :There are chances that product may be leaked through damaged valve or wall which cannot be tracked from control room. Hence opening of ROSOV is given manual so that a person can observe any leakage from outside during manual opening of valve and report to control room.Q10 Why do we use both DBBV and ROSOV in Tanks for delivery and receipt line?
ANS :It ensures safety during receipt and delivery. For product to flow into/out of tank both valves need to be opened. Both valves work on different principle. DBBV (Double Block Bleed Valve) is a motor operated valve which can be opened and closed remotely. On the other side ROSOV (Remote Operated Shut off Valve) can be closed remotely but it is to be opened manually and it is pneumatically controlled.Q11 What is Dyke wall and what its purpose?
ANS :A dyke wall is the boundary of the area consists of a tank or a no. of tank and the height of these dyke walls is provided such that in case of product leakage, these walls should be able to maintain the product within its boundary only.Q12 Why roof of EFRVT are sloped?
ANS :It is provided so that water cannot be accumulated on the roof and via center drain goes out of tank.Q13 How can you access the roof of a Floating Roof Tank
ANS :A rolling ladder is used to access the roof on the FRVT. The top end of the ladder is fixed to the side of the tank, and the lower end is provided with a wheel setup connected to a ramp mounted on the tank. As the tank level lowers or rises, the ladder moves accordingly with the roof height.Q14 Why is a double deck better than a single deck in a FRVT?
ANS :Double deck consists of upper and lower deck, hence it is more rigid. The air gap between upper and bottom plates of the deck provides an insulation effect which helps against solar heat reaching the product and prevents heat loss. Double deck is used in EFRVT.Q15 What is the role of inspection chambers in a ERVT?
ANS :These chambers consist of adjustable legs which can be changed from 3 feet setting which indicates operating level to 6 feet setting which indicates maintenance level.(1/2)
Terminals and Depot 