Vehicle Tank

Ninth Schedule Part I of the Legal Metrology (General) Rules, 2011.

A vehicle tank is an assembly used for measurement and delivery of liquids, mounted on a vehicle. It will have necessary pipe lines, delivery valves and safety equipment. A tank may be subdivided into a number of compartments and each compartment will be treated as a separate unit. Compartments are verified as capacity measure.

Where a tank is fitted with a meter for discharge, the meter will be verified in accordance with the provisions laid down under Part IV of the Eighth Schedule (Meters for Liquids (Other than Water)). The meter should be tested with a liquid of same nature the vehicle normally carry,


The External Side

Markings

The external side should be painted. No and marked capacity of each compartment shall be displayed clearly on each side of the compartments, manhole covers and discharge valves. The markings should be made serially starting from the engine side.

A vehicle should shall have a brass plate revetted at a prominent position for receiving Inspector's stamps.

Other Requirements

  • The discharge and master valves shall be positioned at the lowest point of the outlet so that no residual liquid remains in a compartment after a full discharge.
  • A discharge valve should indicate the compartment no to which it is connected.

Format of Stamping Plate

THE LEGAL METROLOGY ACT, 20009

Name of the company ...............................................
Vehicle tank no ...................................

Compartment Number
Compartment Capacity *
(in litres)
Space for inspector's stamp
      
     

* excludes/includes capacity of delivery line. (Strike out which is inapplicable)

Inside the tank

Datum Plate

Since a tank has an ellipto-rectangular cross section, a horizontal metal plate is fixed at the bottom of the tank in line with the dip pipe. It provides a fixed contact surface from which all measurements are made.

Dip Pipe

A Dip Pipe is rigidly attached to the top of the tank, at manhole of each compartment, and extended vertically downward to about 15 cm height from the tank bottom. It has a diameter of 40-30 mm and have perforations at the top above maximum liquid level. It extends around 25 mm over the manhole cover.

The Dip Stick

A dip stick is the most vital component of a vehicle tank. It is used for determination of depth of the liquid in a tank. It should be made of suitably hard metal bar with regular rectangular or hexagonal cross-section of not less than 15 mm diagonally.

A dip stick should always be inserted through the dip pipe only and should be able to reach the datum plate. All vehicle tanks shall carry only one dip stick, irrespective of number of compartments. Different sides are marked for different compartments

The markings are:

  • Vehicle number
  • Compartment number for which it will be used
  • Proof line for that compartment
  • Marked Capacity of that compartment

Calibration

Equipment and Tools

  • Proving measures tested with Working Standard Capacity Measure within the MPE of ±0.1%. The measures should be placed in overhead gantry above a level platform, preferably made of concrete.
  • The measures will be filled with clean water as the testing medium. You may have to use Capacity Measures of different capacities to reach the desired level.
  • Hose pipe, scriber, punch, try square, tyre pressure gauge, hammer etc.

Preliminary Checking

  • There must be a permanently fixed brass plate to contain the prescribed format.
  • The front and rear tyres of the tank should be at correct pressure with difference within 50 kps.
  • The interior of the tank should be inspected and cleaned for rusting and greases, if necessary.
  • The pipe lines, valves and other connections should be checked for any leakage by partially filling and draining the test medium.

Measurements

The following measurements should be taken and noted in the calibration certificate. The data is mainly used for identification of the tank so that it cannot be changed.

  • The Nominal Length (L)
  • Nominal Breadth (B)
  • Nominal Height (H)
  • Right Sector Length (Sr)
  • Left Sector Length (Sl)
  • Internal Length of each compartment (l1, l2, l3 etc)

The Procedure

  • The procedure should start from the first compartment nearest to the engine. Each compartment should be left with testing medium before proceeding to the next compartment.
  • Each compartment should be filled with with proving measures up to the marked capacity of the compartment.
  • The dip stick should be carefully inserted into the dip pipe (very carefully towards the lowest point so as to avoid any ripple).
  • The dip mark (Maximum Capacity Mark) shall be taken carefully and a line shall be cut the stick at right angles to the axis with the help of a try-square and scriber.
  • The dip stick should also be marked for proof level (the reference level)

Maximum Permissible Error
The Legal Metrology (General) Rules, 2011 prescribes that MPE for Proving Measures will be ± 0.1% and the MPE for vehicle tank compartments will be 0.05% in excess only of the marked capacity for each compartment.

Since, one cannot ensure 0.05% accuracy with 0.1% accurate measures, the practical solution is to allow 0.15% accuracy to vehicle tank compartments.

Stamping

The following places should be stamped:

  • The Data Plate (It must be ensured that the tank itself cannot be changed.)
  • Each marked side of the dip stick