Pipes and other engineering services in industrial building

Dampers make up a critical part of HVAC systems and getting the selection right is vital to long term performance. Here’s what you need to know to choose the right damper.

The basics

Dampers are used to control airflow through certain portions of an HVAC system. You may need them to open and close or you may need them to modulate for variable airflow. They may be duct-mounted, wall-mounted or integrated into air handling equipment. Specialized dampers like smoke dampers limit the spread of smoke through ductwork and air transfer openings.

Dampers are constructed from metal (aluminum or steel) and consist of a frame and moving blades. The position of these blades determines how much air can flow through. Dampers may be have parallel or opposed blade arrangements. Parallel blade dampers are better suited to open/close applications while opposed blade dampers work well for modulating airflow.

Sizing and selecting a damper

Sizing a damper begins with the maximum airflow through the damper using the equation:

Airflow = Velocity x Cross-sectional area.

For dampers, the cross sectional area is the free area, which is the area available for air to flow when the damper is fully opened. Manufacturers publish this information in charts. Once you calculate your free area for a given velocity, use these charts to find the height and width for your damper.

To ensure that the dampers don’t create airflow problems in your system, the fan must be able to overcome the damper pressure drop. Depending on the situation, you may have to oversize your damper to reduce the pressure drop.

Fire damper for fire protection system on the roofing floor.

Choosing a velocity to size the damper depends on the application. The velocity for intake should be limited to 450-500 feet per minute (fpm) to prevent rain from entering. Exhaust velocities can go up to 1200 fpm.

Another decision you have to make when selecting a damper is whether the blades need to be weather-sealed or insulated. Weather sealed and insulated dampers are suitable for intake and exhaust dampers that are open to the exterior.

Controls

Dampers can be manual or automatic and with the increase in building automation, getting control right is important. This is where actuators come in. Our next article will discuss actuators in more detail.

Ever wondered who is legally responsible for the cost of clean-up and repair of damage caused by water leaks in a condominium building? Sometimes it is the association’s responsibility, sometimes it is the owner’s responsibility and sometimes it is either or both of these parties insurance companies less deductibles but here are some tips to greatly assist you in preventing water leaks to avoid the expensive damages the leaks can cause. First, it was found that most of the water leaks in condominium buildings are caused by owners not proactively maintaining and timely replacing their appliances and related hardware; thereby, causing the leaks to occur. The dilemma, however, is that even though this issue of preventative maintenance or replacement may cause the leak usually does not rise to the level of provable legal negligence which, if found, could place the entire cost of clean-up and repair on the owner. Instead, the usual result is that the association and other owners living in units below or next to the leak are having to pay for the costly cleanup and repairs of the damage to the common elements and the other owners’ units caused by the leak.

Following are the items unit owners should consider to prevent the water leaks:

• Contract for ongoing air-conditioning maintenance service, which includes periodic inspection of the system on at least an annual basis, addition of chlorine tablets or other products to keep the lines clear and periodic blowout of the lines.
• Replace unit water heaters after they have been in service for ten (10) years (normal life expectancy of a water heater before probable leaking).
• Replace dishwashers after they have been in service for fourteen (14) years (normal life expectancy of a dishwasher before probable leaking).
• Replace all washing machine hoses with steel lined hoses.
• Turn off main water valve to the unit if the unit will be unoccupied for 48 hours or more.
• Replace the wax-ring, seal and flange every six (6) years or when such activities occur including: toilet beginning to rock, toilet has been lifted or shifted, water leaking from underneath the base after flushing or when the odor of sewer gases has developed.

It is so much better to prevent the water leaks in multifamily buildings up front rather than have to cover the great expense of cleanup and damage repair later. A dry building makes for happy owners and tenants.

Keeping your home safe from flooding isn’t always foolproof, but the more you know and the more cautious you are, the better chance you have to protect your investment. For an added layer of protection, keep up-to-date with the latest technology and Water Security System at the Enolgas USA blog, Facebook, Linkedin, Twitter and YouTube. With everything you learn, you can keep flooding damage to a minimum and have peace of mind. You can’t put a price on that.

However, Mayor de Blasio called this event “a miracle”, and in a press conference went on to talk about how we should be thankful that there weren’t more deaths and damage. Some believe this relaxed viewpoint towards the construction industry a problem that needs to be addressed.

For example, Mayor de Blasio paid more attention to ban horses over his two years span as Mayor, rather than tackling the growing problems with the construction industry. All across the city construction sites are making too much noise. Fines are given out, but they are worthless because the noise pollution is permitted to continue.

Here is a statement that shows how the Mayor fails to take this event seriously: “We’ve had some real serious issues on construction sites. But that is different from what we’ve seen here.”

During the past year there has been a 50% fatality increase causing 18 deaths, and mostly it’s because of negligence and incompetence. The problem here is that the crane owners have killed an individual, but will continue to lift and lower cranes.

This is a real problem that needs to be addressed, but by reading into Mayor de Blasio comments made at the hour-long State of the City speech on Thursday, it won’t be any time soon.

Learn more and read the full article here.