The PED Category online calculator for pressure vessels is a useful tool to calculate the category. Once the category is determined, the conformity assessment module can be selected.

Note 1: Heat exchangers are considered to be vessels, exception: 
Heat exchangers which consist of straight or bent pipes which may be connected by common circular header(s) made also from pipe are classified, and only if, the three following conditions are met:
– air is the secondary fluid,
– they are used in refrigeration systems, in air conditioning systems or
– in heat pumps,
– the piping aspects are predominant.

Note 2: Half-pipe coil or a similar “jacket” construction that heat or cool a vessel are to be classified as vessels.

Note 3: At gas-loaded accumulators, or other vessels with a flexible or non fixed membrane, are made up of two chambers with different fluids, the maximum allowable pressure (PS) and the total volume of the vessel shall be used for classification.

Note 4: If a vessel contains a gas and  liquid, the classification shall be on the basis of the fluid which requires the higher category. The total volume (V) of the vessel, shall be used to determine the category, not the actual volume occupied by the individual fluids at any particular time.

Note 5: If a pressure equipment has several pressure chambers, the categories for the individual chambers must be determined separately. The pressure chamber with the highest category is then decisive for the pressure equipment, e.g. heat exchangers

Note 6: Characteristics (hazardousness) of the solid (contain in gas fluid) should be considered as part of the hazard analysis and do not influence the classification of the vessel.

Note 7: This PED Category Calculator can also use for Pressure Accessories (valve, filters,…). Where both the volume and the nominal size are considered appropriate, the pressure accessory shall be classified in the highest category.