WFI BY PURE STEAM GENERATOR (PSG)

Bram-Cor CPSG Pure Steam and WFI generator

WFI from a Pure steam generator: when it makes sense

The Pure Steam Generator meets the WFI standards

A Pure Steam Generator such as the Bram-Cor CPSG produces dry, saturated steam, which, when condensed, meets USP, Ph. Eur. and JP requirements for Water for Injection. Naturally, the compliance of the steam produced and used depends on the feed water, the pre-treatment methods employed, the management of condensate, and the verification of applicable requirements. In practice this route is a niche solution. It is not cost-effective for large-scale WFI production, but it can be useful when the same equipment has to supply both pure steam and compendial water. For high-volume demand, vapor compression or multiple effect distillation remain the usual choice (see the comparison of MED and VCD).

Pure Steam characteristics

The vapor produced during evaporation consists predominantly of individual H₂O molecules dispersed throughout the gaseous phase.. Contrary to common perception, true water vapor is invisible. What is often observed above boiling water as a white cloud is actually a mist of microscopic liquid droplets formed when hot vapor cools and partially condenses in the surrounding air.

Pure water vapor possesses several notable characteristics:
• It is colorless.
• It is odorless.
• It contains molecules moving at high velocities.
• Its density is much lower than that of liquid water.
• The molecules are largely independent rather than hydrogen-bonded into an extended network.If the source water contains only nonvolatile impurities, the resulting vapor is composed almost exclusively of H₂O molecules and is therefore substantially purer than the original liquid. Clean Steam (CS, a more familiar industrial term in the USA) and Pure Steam (PS, a more closely associated term with the pharmaceutical sector), are dry, saturated steams, suitable also for sterilization of pharmaceutical production plants, for direct contact with Active Pharmaceutical Ingredients (API), for Parenteral and Non-Parenteral dosage form applications.

 

Bram-Cor-cpsg-st-200-

How a Pure Steam Generator works

Pre-treated purified water is heated above boiling temperature in a double tube sheet heat exchanger. The steam expands into an evaporation column designed to keep steam velocity low, which limits the entrainment of water droplets. Residual droplets are removed by centrifugal and gravity separation. Pure steam pressure is maintained by an electronic control system that modulates the supply steam valve and monitors the evaporator feed water.

The generator is fed with Purified Water and heated mainly by plant steam (typically 6 to 8 barg), but also by electricity or superheated water. Capacities range from 20 to 8000 kg/h. Design and construction follow cGMP and PED criteria, with certified materials and instruments and welds made by qualified welders. In detail:

  • The evaporation column is designed to minimize steam speed to avoid the entrainment of water droplets, which are separated from the steam by means of a special separator.
  • A Double Tube Sheet Heat Exchanger provides heating of pre-treated feed water above the boiling temperature, generating pure steam which expands into the evaporation column. The heating medium in the DTS Heat Exchanger is typically industrial steam at 100 to 120 psig (6 to 8 barg).

Pure steam pressure is maintained by an electronic control system, modulating the supply steam control valve and monitoring the evaporator feed water.

Technical Features

  • cGMP design and construction; all product contact surfaces in AISI 316 L stainless steel.
  • Jackets, frame and control board in AISI 304 stainless steel; all welding is performed by qualified welders.
  • Gaskets in EPDM or PTFE or Silicone; pneumatic valves with Teflon/PTFE membranes and AISI 316 L SS polished body; ASTM C-795 – compliant insulation.
  • Instruments: conductivity meter, pressure transducers, temp. probes & level transmitter.
CPSG-ST-diagram

 

PURE STEAM - quality critical attributes
PHYSICAL / CHEMICAL Ph. Eur. USP
Conductivity

≤5,1 µS/cm 20°C

≤ 1.3 μS/cm 25°C
TOC ≤  0.50 mg/L ≤  0.50 mg/L
MICROBIOLOGICAL Ph. Eur. USP
Bacterial count ≤ 10 CFU/100 ml ≤ 10 CFU/100 ml
Bacterial endotoxins < 0.25 EU/ml < 0.25 EU/ml

30 09 2026. Values from Ph. Eur. (12^ Ed.) and USP 48 – NF 43

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