Acid & Caustic Applications

When working with high alkaline media (high pH) or high acidic media (low pH), extra care must be taken in the design and selection of the Fluid Handling System.

At some point, most industrial processes include fluidic media for cleaning, purifying, diluting, distilling, coating and/or other fluid handling functions. A critical characteristic of this media is its pH measurement. This log measurement is a normalized scale which reads the free hydrogen active in the solution (pH = -log[H+]).

The pH Scale ranges from 0 to 14, zero representing a highly acidic media, and 14 representing a highly alkaline media. Both pH extremes can be very corrosive to piping, tubing, fittings, valves, filters, pumps, tanks and other fluidic devices.

The pH Scale can be grouped into five basic ranges:
0 to 4 = Acidic
4 to 6 = Slightly Acidic
6 to 8 = Neutral
8 to 10 = Slightly Alkaline (Base)
10 to 14 = Alkaline (Base)

In general, when the pH reading of the media drops below 4 or raises above 8, manufacturers and/or process engineers will shift their designs towards High Purity Fluid Handling polymers, such as: PTFE, PFA, PVDF, PEEK and Polypro.

By design, throughout the Fluid Handling process, pH Adjustment Systems raise and/or lower the working pH Level of the media. Wet Bench Systems and Fluid Handling Skids are designed to dilute concentrated chemistry for industrial process use. Others are designed to analyze the chemical media, and dose and adjust the chemical media to maintain the optimum chemical blend. Others are used specifically for chemical etching, cleaning, and coating.

A special class of equipment called pH Neutralizing Systems are actually pH Adjustment Systems configured to raise and/or lower the media's pH back to the neutral state (~7.0 pH).  These systems blend acidic and alkaline media to achieve close to the classic neutral reading of pH 7.  The neutralization serves multiple purposes related to the storage and disposal of the process media.  The resulting salts and process metals can be filtered out of the media.  These systems frequently further dilute the neutral filtered chemistry to a condition where city sewage disposal is possible.

For example:

A typical pH Adjustment System (process skid) could be used to neutralize Hydrochloric Acid (HCL) for disposal. The system would blend Caustic Soda (NaOH), or Sodium Hydroxide, to raise the pH to 7.

The titration would create water and salt: HCl + NaOH ==> H2O + NaCl

These Wet Bench Process Skids work in discrete batch form or continuous flow form. They can be designed as simple Holding Tanks with open manual measurement and blending stations, or highly automated with full PID Control Loops for continuous process adjustment.

These types of systems are frequently custom or semi-custom designed for the application. They include Laboratory Waste Water Recovery; Semiconductor post cleaning, etching, plating Acid Neutralization; and Suspended Metal Extraction.

Because of the exposure to low pH Acidic media and high pH Alkaline media, the Fluid Handling devices must be selected to manage the corrosive nature of the media.

iPolymer

iPolymer offers a complete line of High Purity Fluid Handling products, including:

• PTFE Solenoid Valves
• PTFE Pneumatic Valves
• PTFE Ball Valves
• PTFE Drain Valves

A short list of popular neutralizing chemicals we've handled in the past are:

Acids

• Sulfuric Acid (H2SO4)
• Hydrochloric Acid (HCI)
• Nitric Acid (HNO3)
• Phosphoric Acid (H3PO4)
• Carbon Dioxide (CO2)

Bases

• Caustic (NaOH)
• Ammonium Hydroxide (NH4OH)
• Magnesium Hydroxide (Mg[OH]2)
• Calcium Hydroxide (Lime) (Ca[OH]2)

These types of Acids and Bases require High Purity Polymer Fluid Handling solutions. The basic fluid handling category is Acid Valves and Acid Fittings. Our Acid Valves and Acid Fittings are manufactured from 100% pure virgin PTFE. Field proven, with over 30-years of experience from our two acquisitions: TEQCOM Industries and BECO Manufacturing, iPolymer is a global leader in PTFE Fluid Handling Solutions.