Eliseu Portugal Jersey

[ruan123]

The term “sound” is used for air or other gas while “vibration” is used for a similar disturbance of motion in a solid. The sound pressure disturbance impacting on a solid can impart a vibration while the vibration of a solid can result in sound. Some prefer to call the concept of vibration which results in sound “structure borne noise.”

There are two types of noise problems — those that we anticipate from our sound ratings and those emanating from some abnormal condition in the fan. Some of the more common sources of abnormal or unanticipated noise are:

1) Fan wheel unbalance.
2) Resonance of fan or attached components.
3) Rotating components rubbing on stationary parts.
4) Failing Miguel Monteiro Portugal Jersey , misaligned, or contaminated bearings (on the fan or on the motor).
5) Air leakage. This can allow sound leakage and also generate a whistle-type noise.
6) Belts slipping.
7) Coupling misalignment.
Motor noise, especially with improper power supply. Inverter drives may increase motor noise at certain speeds.
9) Air turbulence.
10) Operation in surge.
11) Loose components.
12) High velocity air blowing over fixed components which are not part of the fan.

The other class of noise problems are those we have anticipated because of normal fan sound ratings. Some cures for these problems are:

- Select a different fan. Computerized selection routines allow us to examine many fan types looking for the quietest. Use a custom fan design Jose Fonte Portugal Jersey , if required.
- Relocate the fan to where sound is not a problem.
- Vibration isolation and flexible connectors on the inlet and discharge will reduce structure-borne noise.
- Insulate or acoustically enclose the fan housing if housing radiated noise is a problem.
- Add silencers or duct lining to inlet and or discharge to reduce sound in these directions. However, a silencer on the outlet does not reduce the housing radiated noise or inlet noise; and an inlet silencer does not affect the housing radiated andor outlet noise.
- Look for ways to reduce system resistance since sound output is proportional to fan static pressure.

One final tip which can help to avoid noise problems is to select lower RPM fans. Fans exceeding 3000 RPM are much more likely to tune in to an attached structure resulting in structure borne noise. Structure borne noise easily propagates an entire system and can become a problem at many locations. Also, people tend to become more annoyed with higher frequencies than with lower Joao Moutinho Portugal Jersey , increasing the likelihood of a noise problem.

Recently, several changes are developing in the technology of fan noise. Some of these are:

1. The latest codes define testing for fan inlet noise, fan outlet noise Joao Mario Portugal Jersey , and noise radiating from the housing (or casing). The inlet noise can no longer be assumed to apply to the outlet and vice-versa.
2. A new test code which uses sound intensity is near adaption. In theory, integrating a series of measured sound intensities over an enclosed area yields the sound power directly.
3. Sound criteria is playing an ever more important role in the selection process. Many fans are insulated for sound or use other sound reduction apparatus.
4. Active noise cancellation continues to be difficult to apply to most fan installations. If it ever proves practical, this technique can cancel fan noise by adding a second pressure wave out of phase with the original.
5. Many more fan specifications are requiring AMCA sound certification. Certified sound ratings mean that AMCA has verified that the ratings are generated in accordance with the codes and that at least one sample has been tested in the AMCA Laboratory to verify the ratings.

Additional information can be found at the Canadian Blower company web site http:www.canadianblowerahuindex

Oleg Tchetchel
Air Handling Systems Engineer
oleg.tchetchel@canadablower
Canadian Blower
http:www.canadianblowerinquiryindex
http:www.canadianblowerairhandlerindex IPL machine can be used to treat the face Fabio Coentrao Portugal Jersey , chest, neck, and hands Eliseu Portugal Jersey , and treatments only take 15 to 30 minutes per session. Almost anyone can be a candidate for this procedure but only your doctor can fully determine if your skin type is compatible with IPL. This treatment is a painless alternative to chemical or laser peels and in many cases patients report a reduction in pores and smoother skin. IPL is a quick, non-invasive procedure and best part is that there is virtually no downtime.

Prior to your first IPL treatment, you will meet with your doctor to discuss your goals and to determine the best way to treat your problem area. Your doctor will perform a spot test on the desired area to see how your skin reacts. This procedure is very simple and consists of emitting high intensity pulses of light to the skin. Different machines are used for various levels of penetration.

A topical anesthetic can be used to ensure your comfort if desired and you will be given dark glasses to protect your eyes from the bright light. A soothing gel will then be applied to the face and a glass pyramid will be placed on top of the gel. The pulses of light will go through the pyramid and treat the desired areas of your face. There are filters in the handpiece that control the wavelength range allowing for different applications and skin types.

The light passes through the facial tissue where it is then absorbed by either blood or melanin. The injured tissue is then removed by the body's natural processes and the skin appears fresh and even. The first session of IPL will not be very aggressive in an effort to not aggravate the skin. You will have treatments every 3 to 4 weeks Eduardo Portugal Jersey , and the intensity will increase with time, that is. Wholesale Jerseys From China Wholesale Jerseys China Wholesale Cheap Jerseys Wholesale Authentic Jerseys Wholesale Jerseys China Free Shipping Wholesale College Hockey Jerseys Cheap NBA Jerseys Free Shipping Cheap College Hockey Jerseys Wholesale Authentic Soccer Jerseys Cheap Jerseys From China