Friday, August 31, 2007

Condensate Polisher Vessel Materials of Construction

We often receive the following question about the materials of construction of condensate polisher vessels.

Question: We're considering a condensate polisher in our boiler plant. Should the vessel be constructed of carbon steel or stainless steel?

Answer: Over 75% of the condensate polishers that Res-Kem builds utilize stainless steel pressure vessels. If you use a carbon steel vessel it will have to be provided with a high temperature liner for corrosion resistance. For a condensate polisher with a diameter of 30" or less, the liner can not be installed working from inside the tank and the quality of the lining is unpredictable. In fact most liner companies will not warrant their linings if the vessel diameter is less than 36".

Stainless steel vessels cost a little more however the entire lining issue goes away as one is not required. For condensate polishers 30" or less in diameter it does not make sense to even consider a carbon steel vessel with a liner.

Res-Kem builds a very economical line of standard stainless steel condensate polishers from 20 inch to 66 inch diameter vessels . Our standard designs employ stainless steel vessels, flanged and welded stainless steel face piping. Depending upon the size of the valves we use stainless steel Aquamatic diaphragm and/or butterfly valves. To save a little money, we have an option for smaller size systems using stainless steel vessels, threaded steel face piping, and cast iron Aquamatic diaphragm valves.

Thursday, August 16, 2007

Aquamatic Valve Selection and Pricing

A common inquiry we receive at Res-Kem is a customer looking for a price and delivery on an Aquamatic Valve. We, in turn, ask the customer the following:
  • What kind of Aquamatic valve is used on the equipment?
  • Is the valve normally open, or is it normally closed?
  • Does it have a limit stop or a position indicator?
  • Is there a Spring Assist Open or a Spring Assist Closed option?

    Knowing the type of valve allows us to properly provide an accurate estimate and insure you receive the correct valve for your application. In most cases, it's hard to identify a valve because the equipment is old, corroded, and/or there is no longer a parts list for the system. So, where does one go from here? We hope to provide some insight into ways you can determine the type of valve you have in order to get the correct price and valve.

    The best way to identify the valve is to know the Aquamatic Valve Model Number which is a 13 digit number that describes the valve.

    A GE Aquamatic Valve Model Selection Guide helps determine the valve type and some options. Each valve series has its own Valve Model Selection Guide. Customers more than likely do not have this number because, again, it is an older system with no parts list. Typically, Aquamatic valves will have the valve series cast or molded into the valve body. For example, a V42 series valve is the common cast iron Aquamatic Valve. If you look closely on the body of the valve, you will see a 3 digit number, such as, 421 or 424. The 42 would indicate the series, and the 1 or 4 indicates the size.

    GE Aquamatic V424 Series valve showing metal indicating tags

    The Aquamatic Composite Valves are the K52 & K53 series. Again, on the body of the valve, you will see a 3 digit number for these valves, 521 or 535. The 52 and 53 specify the series, and the 1 or 5 represents the size.

    GE Aquamatic K524 Series valve showing molded in valve description

    Now that we have figured out the type of valve, lets take a look at some ways to determine the configuration of a valve.

    Is it Normally Open or Normally Closed?
    The most common Aquamatic Valves have two ports positioned on the top portion of the valve cap and along the side underneath the cap. They are usually an 1/8" or 1/4" female NPT port. If the NPT port on the top of the valve cap has a a pipe plug, the valve is a Normally Closed Valve. If there is no pipe plug at all on the ports, the valve is Normally Open.

    Limit Stop or Position Indicator?
    Limit Stops and Position Indicators can be easily identified on valves. Limit Stops are adjustment screws or bolts which limit the valve stroke. They are primarily used to control the flow rate. Position Indicators are small rods attached to the main valve stem which are used to show the position of the valve. One thing to note: if you have a valve with a position indicator, you will not have a Spring Assist Closed Valve since those two options cannot be combined.

    GE Aquamatic K53 Series valve showing a position indicator and marking of SAO (Spring Assist Open)option

    Spring Assist Open or Spring Assist Closed?
    These options are typically used to assist full opening or closure in the absence of line and control pressure. It is also difficult to determine if one has this option because the springs are inside the valve cap. With the composite valves, the valve caps look the same if there is a spring option or no spring option. If you look closely, the letters SAO or SAC are usually marked on the valve body of the composite valves; however, that mark tends to wear off over time.

    The Spring Assist Closed option can easily be identified on the metal diaphragm valves because the valve cap is noticably different.

    GE Aquamatic V42 Series valve showing a Normally Closed Valve and Spring Assist Closed option

    These valves also come with metal tags that indicate the options. You can find these tags secured to the valve cap hex screws. The tags could get broken off, so you do need to check to see if there was a tag on the valve cap. If all else fails, the best way to determine if you have this option is to remove the top cap to be certain.
  • Water Testing Services Offered

    Before purchasing any water treatment equipment, the first piece of information a person should obtain is a water analysis. The challenge is you want a quick, independent test at an affordable price. While we can not vouch for it at this point, an employee may have found a reliable third party testing service for Pennsylvania residents. He found an article in the Town Talk Newspaper of Delaware County about a service offered by Penn State's College of Agricultural Sciences. The College has an Agricultural Analytical Services Laboratory which offers water testing to the general public.

    The laboratory has a list of standard analytical packages that range in price from $50 - $130 per sample. Also, the laboratory has a list of individual analyses for drinking water.

    To submit a drinking water sample to Penn State’s laboratory, you must first obtain a Drinking Water Test Kit. Kits are available at many county cooperative extension offices or may be obtained directly from the laboratory. The kit consists of a shipping box, sample bottles, instructions on how to take a sample, and a submission form. After taking your water sample, you must send the kit to the laboratory by overnight mail along with your payment for the test(s) requested. For the bacteria test, included in all test packages, the laboratory must receive the sample within 30 hours after sampling.

    How soon will you get your results? According to the Agricultural Analytical Services Laboratory's website, tests are complete within two weeks after sample receipt by the laboratory. With mailing time, you should receive your report within two to three weeks after sending your sample.

    Tuesday, August 07, 2007

    Activated Carbon Prices Going Up Again!

    I just had a meeting with Calgon Carbon Corp. to discuss new pricing, again. The tariff decision here in the US and the Chinese VAT change conspired to increase the cost of activated carbon regardless of manufacturer. In addition to these changes, the worldwide demand for activated carbon has increased substantially, so "supply & demand" pressures can be added to the mix.

    It's always hard to tell customers when prices go up, but it's not something we as an OEM can control. Res-Kem Corp. continues to get the best available pricing on Calgon Carbon, but we can't absorb the price increases. These need to be passed along to the end-user.

    Before you buy your next load of activated carbon, you might want to re-evaluate your application, equipment operation, and activated carbon selection. Keep in mind the following:

  • Chlorine is easy to remove- To most efficiently remove chlorine, choose the carbon with the highest surface area, not the highest iodine number. Activated carbon with a high iodine number typically is a more expensive option.

  • Confirm whether you are removing chloramine or chlorine- Check with your water utility to determine whether they are chloraminating or chlorinating the water coming to your plant. There is a difference in capacity for chloramine vs chlorine. You will need to consider using a different activated carbon for more effective capacity. It may cost more but it will last longer and be more effective.

  • Organic removal- To most efficiently remove organics, look at the iodine number, BUT remember this is a good measure of how much iodine or similarly sized molecules the activated carbon is capable of removing. If you have the option, consider trialing different types of activated carbon to determine which works best for your application.

  • Review your operating procedures-
    Are you backwashing too much or too little? Activated carbon filters don't necessarily need to be backwashed every day. Res-Kem recommends backwashing based on pressure drop in most cases. Unlike steam activation, backwashing the activated carbon filter doesn't extend the life of the activated carbon.

    Unless you are using treated (carbon-filtered) water, activated carbon filters, used for the removal of contaminants such as VOC's (volatile organic contaminants), should not be backwashed at all. Any time you backwash an activated carbon filter with raw water you run the risk of contaminating the bottom portion of the bed.

    Bottom line - water costs money and you might be using too much if you are backwashing too frequently. Consult with the manufacturer or the activated carbon equipment manufacturer or Res-Kem if you have questions.

    Are you losing activated carbon every time you backwash? Be sure the backwash rate is set correctly. Activated carbon weighs anywhere between 16 and 31 pounds per cubic foot. If you change the type of carbon you are using, make sure the backwash rate is set properly. If you set the rate too high, you run the risk of floating the carbon out of the tank. Conversely, if the rate is set to low, the bed is not cleaned sufficiently for full effectiveness.

  • Are you able to monitor the contaminant levels? If you are running activated carbon filters in series, be sure to monitor the first bed of the series for contaminant breakthrough, IF you have the means of measuring for that contaminant. Change out or rebed the activated carbon filter only when it is fully exhausted, that is when the first undesirable contaminant shows up in the effluent water of the first tank. If possible, make that newly rebedded activated carbon tank the polishing tank and begin to monitor the older tank for breakthrough.

    If you have other ideas for more effective ways of saving money when operating activated carbon filters, let me know. I'll be happy to pass on the knowledge.
  • Wednesday, August 01, 2007

    Automation and Control of Water Treatment Systems

    Res-Kem receives requests for quotation and information to automate and control industrial water treatment equipment like activated carbon, water softeners, reverse osmosis systems (RO), DI, service DI, electro-deionization (EDI), continuous deionization (CDI), ultrafiltration (UF) mixed beds, sub micron filtration, etc. using electro-mechanical timer/stagers and programmable logic controllers. We can readily respond to these requests.

    In addition, Res-Kem has been receiving requests for quotation and information to automate and control other water systems for:
  • Odor Control
  • Influent Clarification
  • Cooling Towers
  • Boilers
  • Waste Treatment
  • Remote & Online Monitoring
  • pH Neutralization
  • Wastewater Control
  • Environmental Monitoring
  • Environmental Sampling
  • Material Handling

    Res-Kem is now able to offer solutions to these automation and control needs.