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Get cash rebates to cut water use

Owners of facilities served by utilities in the Saving Water Partnership can get rebates up to 50% for upgrading steam sterilizers, medical air and vacuum systems, x-ray processing and other medical equipment. View medical rebates >

Steam sterilizers/autoclaves

There are two basic types of machines: gravity and vacuum. During standby mode, condensate is constantly formed and discharged from the chamber. This relatively constant flow is tempered (cooled) by using cold fresh water at a constant flow before being allowed to discharge into the sewer. This form of trap cooling is in effect 24/7 unless the machines are turned off. It is very common, however, to leave this equipment in standby mode.

A trap cooling retrofit kit will allow the exiting hot condensate to cool in an expansion chamber and is monitored for temperature. When the desired temperature is reached, discharge can occur without using any, or very little, cold fresh water to reduce the temperature further.

A vacuum autoclave uses water flow to create a vacuum during the drying phase of the sterilization process. The rate can be as high as 14 gpm once-through constant flow. A new water-conservation technology is to install a vacuum switch in series with the ejector solenoid valve that controls water flow. When the desired vacuum in the autoclave chamber is reached, the solenoid valve is closed and the flow of water is interrupted.

Typical savings for the trap cooling retrofit kit is above 90% which leads to a payback of less than one year at a cost of about $2,500 each. Savings for the vacuum switch has been verified at 35%. Depending on how many cycles per day the unit completes, savings can over $2,000 per unit, again providing a payback of approximately one year or less.

Medical air and vacuum systems

Once-through liquid ring medical air and vacuum systems are reliable, but, like the use of other once-through water cooling technologies, has become very costly because of the associated large consumption of water and then the cost of sewer discharge. Another factor is energy efficiency. Given the age of many of the units still in use, energy efficiency can be enhanced significantly by switching to new air-cooled units installed in series with variable speed motors and sized to come on in stages based on

the load required. With high-efficiency motors, overall horsepower is reduced, and less-than-full-load horsepower is greatly reduced. It’s a win-win for water and energy, with combined energy and water rebates often available.

Other medical equipment

Glass washers, cart washers, cage cleaning stations, electron microscopes, image processing, reverse osmosis (RO) production and more could consume high quantities of water in medical or lab settings, and very likely have potential for better water use efficiency. The options will normally fall into these general areas:

  • New air-cooled versus water-cooled equipment
  • Reducing number of rinse cycles like in a glass washer
  • Using already used water when lower quality can produce equal results compared to fresh potable water like in a cage cleaning station.
  • Recirculate water for continued use like in a water-cooled electron microscope.
  • For RO production increase the production rate and decrease the reject water, or capture the reject water and use in another process like a cooling tower, or a cleaning process.

Water purification and reuse

Take steps to conserve water in your purification processes and consider reusing water:

  • Evaluate all reverse-osmosis, de-ionized, or other water purification systems and make certain they are operating at the highest efficiency for the product water needs.
  • Consider using unwanted water for other purposes such as cooling tower water, cleaning processes, or cage washing.
  • Use this Reverse Osmosis system checklist (docx) to get the most out of your system.

Contact

For more information contact Arece Hampton at arece.hampton@seattle.gov or (206) 733-9137.

Resources

Green Business Program can help you develop individual business solutions to save water and lower utility bills. Phone: (206) 343-8505

Cost Savings Calculator (xls) – Estimate savings on utility bills by switching to more efficient equipment, technology and procedures.

Cool Tunes Manual (pdf) – See savings through consistent monitoring of chemical, conductivity, water make-up and blowdown, any unusual spike in water consumption.