Carbon Dioxide, CO2, Detectors monitor spaces occupied by people or animals to remove excess CO2, which is a byproduct of breathing.  High levels of CO2 are associated with what is known as “Sick Building Syndrome“.  Most building code regulations require a certain amount of air replenishment, or turnover, to avoid high buildup of CO2 and the resulting health problems.  CO2 Detectors are typically available with adjustable setpoints, analog signals, and one or more relays.

Carbon Monoxide and Nitrogen Dioxide, CO, NO2, Detectors are utilized in spaces where internal combustion engines are operated: parking garages, service garages, small engine shops, warehouses, underground garages, generator rooms.  Carbon Monoxide is a byproduct of the combustion of gasoline, where Nitrogen Dioxide is a byproduct of the combustion of diesel fuel.  Much like CO2 controllers, these units monitor gases and send a proportional analog signal, and/or make relay contacts to stage fans in order to replace toxic air in a given space.

While it is possible to just maintain a constant ventilation rate, that is typically not preferable as ventilation rates should match demand and with these gases demand typically varies.  In addition, as noted in a previous post, building ventilation and the associated building pressure should be balanced.  Therefore, in most cases a demand-control system is preferable.  This type of system will remove toxic air as needed, and at the same time replace that air with an equivalent amount of fresh make-up air.  The driving factor in the system is a properly-applied IAQ Gas Detector/Controller.

RJ Owen Associates offers gas detectors by Brash Manufacturing and other manufacturers, system analysis, design, installation, commissioning, replacement and repair services.  336-869-7579

The best place to start with a steam trap maintenance program is to have a steam survey done by a qualified steam specialist.  A proper survey will map out all the traps; test and note their condition; place an identification tag on the trap and note it on an accompanying spread sheet; make recommendations for repairs or replacement; and note any piping irregularities, misapplications, improper applications, and recommendations for efficiency improvements.  The initial survey acts as a baseline for a steam system PM program.  The best approach is to implement a regular testing schedule and replace failed steam traps as they are discovered.

The job of the steam trap is to remove the condensate from the steam system but not allow any steam to escape in the process.  Failed traps typically either blow through, allowing all steam to escape; fail closed, not allowing any steam to escape; or leak by the seat, not providing a good seal and allowing some steam, but not all, to pass through.  In terms of trap failure, these are the most common scenarios.  A common finding on steam trap surveys is misapplied traps, where someone replaced a trap with one that was not appropriate for the job.  In many cases a misapplied trap will not work well enough, or not at all if it’s not sized for the correct conditions.

I will cover the process for testing traps in the next entry in this series.

RJ Owen Associates has a complete selection of steam specialties and provides technical training, steam system surveys, technical service, and product support.

The best solution for negative space conditions is forced make-up air.  In some cases this can be accomplished with a supply fan (fans) that matches the amount of air being exhausted.  However, in most cases the best approach is to temper the make-up air as well to provide for employee comfort and/or a consistent process environment.  While comfort cooling is possible with make-up air, it is harder to accomplish and typically more expensive.  The most common approach is to heat the air in colder months, and supply non-tempered air in warmer months.  Make-up air is typically heated with gas, steam, hot water, electrical strip heat, and sometimes heat pump technology.  In some cases a mixing box can be used to mix the warmer air that rises in the space with the outside air to temper the air.

Sizing a make-up air unit is often as simple as matching the supply volume to the amount of air being exhausted.  It is often advisable to oversize a little, (+/- 10%), to ensure the space is positive.  However, there may be other considerations such as heat loss or other negative pressure influences from adjacent spaces that need to be accounted for.  Another major consideration is heat load for heated make-up air.  While it is a fairly straightforward process, there are several variables to be considered when sizing and selecting make-up air systems.  I will address these in further entries per topic.  For now, suffice it to say that make-up air is crucial for healthy happy employees, consistent process environment, and in many cases state and federal regulations.

RJ Owen Associates offers make-up air systems from Weather-Rite, LJ Wing, Brasch Manufacturing, and Canarm.  We have solid experience in the design, selection, installation, start-up, commissioning, repair, and service of all types of make-up air, heating, and ventilation systems.

I find it much better to use steam injection for humidification.  This of course has its problems as well, but technically is far superior as the moisture being absorbed is already at steam temperature and thus doesn’t require the loss of BTUs from the surroundings.  The problems mostly come in sourcing the steam for usage.  Injecting boiler steam is the easiest method, but it results in a loss of boiler capacity and some (albeit a slight amount) of water treatment chemicals.  An alternative to that is indirect, or steam-to-steam, systems that utilize heat exchangers to heat and inject a separate water source, thus saving on boiler capacity, boiler water, and treatment chemicals.  A bigger and more frequent problem is the lack of steam onsite altogether.  There are simply less and less building and utility systems utilizing steam.  This can be remedied with a small boiler or steam generation systems, or packaged humidifier systems.  Technically these are more efficient than misting systems in general.  However, the upfront costs are typically higher.  Up-selling to these systems can be difficult depending on the application and specific customer needs.

The typical industrial misting system consists of a high pressure pump @ 800-1200psig, feed lines, injection nozzles, and sometimes fans depending on the space and needs.  Some systems utilize stainless steel feed lines, typically mounted above worker spaces with injector nozzles at predetermined distances and no fans.  Others will utilize fans with nozzle rings face-mounted.  These systems are very applicable in high heat, low humidity environments, low worker-per-square-foot areas, and milder climates.  I have found several applications in flammable locations where low humidity causes static electricity and danger of explosions.  This has been a good technology for these applications and in low budget situations.

As in all things mechanical, applying these systems depends on an infinite number of variables.  While ultimately I prefer steam injection, high pressure misting is an acceptable alternative.

The impact for those of us closely tied to manufacturing is obvious.  But this downturn is not so selective.  It appears to be affecting everyone.  It not a select industry or specialty group that is feeling the brunt this go-round.  This is an equal opportunity recession.  It is affecting the banker and the backhoe operator, the engineer and the trucker.

You will notice my emphasis here is a human resources one.  I’m not even getting into the macro-economic side of this, although I am very interested in and equally confused by that.  What I am finding as a business owner is that it is not any easier than when I was an employee.  The bottom line is still the bottom line, still important, and still directly related to my paycheck.  I am like any of the other middle aged managers mentioned in the Wharton article.  I need to diversify, find other opportunities, make myself more valuable yet again.  The big challenge is, given the current environment, how do I go about that?

How indeed!

The typical freeze scenario comes into play because of system stall.  Conventional steam coil design utilizes a modulating valve to control steam flow.  Now, while I note this is conventional design, it is not necessarily optimal design.  In most cases of using steam in HVAC applications I recommend the Integral Face and Bypass Coil, as noted in a previous entry.  However, that design is not in itself always optimal, or always utilized; in which case the designer, plant engineer, or technician must deal with the situation at hand.  As it stands, conventional design utilizing a modulating valve will run into trouble at the point the valve begins to close as demand is satisfied.  If in this situation the valve closes so that downstream pressure is equal to or greater than upstream pressure the coil will be in a condition of stall.  The condensate will accumulate in the coil and is thus subject to freezing.

My choice solution for an existing conventional system is to utilize a freeze valve that will sense the water and remove it.  I use the Thermomegatech HAT valve with a setpoint of 100 Deg. F.  I install the valve in the condensate line between the coil and the strainer and/or steam trap.  I pipe the condensate to drain.  I have seen similar devices used by the steam specialty companies that were marginal or ineffective.  The primary reason being they had a setpoint in the area of 35 Deg. F.  This is too low and too close to freezing temperature.  The condensate may not be able to escape the coil before freezing.  On the other hand, having a setpoint of 100 F. seems to work well.  100 F. is way too cold for condensate, which should typically be over 210 Deg F., yet it is warm enough the condensate won’t freeze.

I have had positive results with this system.  While it is recommended for conventional steam heating, it can be applied in most applications where freezing condensate or system stall may be a problem.  Another problem with system stall outside of freezing is the introduction of air and non-condensables into the system through the vacuum breaker.  This is often seen in process heat exchangers utilizing modulating valves as discussed above.

HAC&R

Thanks, Mohamed!

“Compared to hot water, there are several advantages to steam.  Due to higher energy content per mass, the required heat transfer area is smaller, heat coefficients are higher, distribution pipes and necessary plant sizes are smaller.  Rather than costly circulating pumps and the relatively larger components needed for hot water systems, steam is distributed and controlled through pressure differentials.  However, utilizing the heat of steam requires its condensing, which can be troublesome.  In fact, condensate and its removal are the source of most of the problems associated with steam heating.  To effectively take advantage of steam’s higher energy content and flexibility, the byproduct, condensate, must be controlled and utilized so as not to hamper heat transfer, or, worse, lead to frozen or damaged coils.”

Download the article in pdf here.

Enjoy.

I am mainly stating the obvious here.  I am not decrying international trade, nor longing for the old days.  What we have is what we have.  The work ahead of us is focused on making proper use of what we have.  There are still uses for steam technologies, evaporative cooling, direct gas-fired make-up air, and process controls.  The challenge I think is re-imagining the world, seeing things differently.  If we continue to look at the world based on the way it was we will miss out on the way it will be.  That being said, I don’t have the answers.  But hopefully I have enough imagination and fortitude to find a way to make it all work out for me and my business.