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Thanks guys, Pump manufacturer had already come and dismantled the pump. The only statement from them is the problem is because of suction condition and it is out of warranty. However, they did not explain the reason of the problem in detail. I try to analyze operating conditions. Pump's flow...

Thank you chicopee. It makes sense for me. I focus on that issue. Artisi, as we are engineers, i certainhly post here. I believe that somebody will help, you may not.

Hi Guys, We have a boiler feed water pump operating. Recently, i have learned that it stopped working. Pump has been tripped. Shaft is not able to be turned by hand. I have checked cavitation theoretically, eveything is good. Moreover, when pump is not in operation water temperature drops to...

Can you please give us a drawing showing all dimensions, all equipments and flow rates? First, you need to analyze the design to find noise isuue.

The answer is both no and partly yes. First of all, if you need to reduce relative humidity, you need to cool air and take its water content. Therefore, you decrease DB. However, when you finished to decrease water content, then you can heat air to the inital DB. Then, you have DB unchanged and...

Ventilation rate is given as roughly 7.5L/s-m2 for parking garages according to Table E-2 from ASHRAE Standard 62-2001 Addendum n. (please note that exhaust not required if two or more sides comprise walls that are least 50% open to the outside) However, It is 300L/min for min. according to NFPA...

Hi Ogsray, Is there possibility to fill all 6 basement carpark floors at a time? If it is so, diversity does not work to size shafts. I think shaft is sized according to the max air flow rate and you can put more than one fan with frequency drive. Therefore, you can fulfill the full air flow...

Hello, Cooling tower cools water by evaporation and evaporation occurs at any temperature. In detail, air flow evaporates some at the surface of water droplet and water temperature decreases. In that process, water temperature approaches to the wet bulb temperature (min. 5oC difference between...

Hello, Recommended noise rate for office area is RC 25-35 according to ASHRAE Sound and Vibration Controls. It had better to look at octave band sound pressure levels. For office (assume NR30), noise levels are 57db, 48db, 41db, 35db, 31db, 29db and 28db for 63Hz, 125Hz, 250Hz, 500Hz, 1000Hz...

Hi Emalysd, Make-up air is usually supplied the edge of the hood to prevent the smoke release to the kitchen area. Theoretically, all make-up air should be exhausted by the hood. However, it is hard to say that since there may be turbulence in make-up air flow and some of air is released to the...

Hi Stadamack, Possibly you mean 20L/s per something! Right? According to DW171, there is method-7 finding approximate flow rate for canopies and stating that 15-20L/s air extraction per kitchen area. What i try to say you miss something, after clarifying this, maybe we can help. Regards, Emre

No, indoor unit must satisfy the sensible heat load first, then check the latent load later.

Hello yfuo28, There are more parameters than you think, it affects chiller performance directly and indirectly. Firstly, air temperature is the parameter that you should think since your water circuit is cooled with air. As air temperature is low, chiller performance is increasing because...

The cooling capacity of air conditioners is usually measured in tons. One ton equals 12,000 BTUs (British Thermal Units) per hour. The term one ton comes from the amount of heat required to melt a block of ice that weighs one ton. 1 TR = 3.5167kW Therefore, it had better to ask what ton of...

Hi Russell, The calculation is wrong. The phenomena is called as "thermal gravity effect". You have to compare the air inside the duct and ambient air. when air in the duct is hot, then it rises even roof fan is not in operation. Air is cold then it goes downward. How it is calculated is as...

Hi Folks, Have you ever experienced or seen Active Noise Cancellation or Control in HVAC ducts? I have read articles about the system but have never seen this system being used in HVAC ducts. It is effective to diminish sound with low frequencies up to 500Hz. By this way, this is very effective...

If you have cad drawing of the existing ductwork, it had better make engineering calculation such as duct acoustic calculation with respect to octave band frequencies according to ASHRAE HVAC Applications Sound and Vibration Control. It will give you sound levels at any point in your system...

According to "Sound and Vibration Control" Chapter Section 46, Table 4; maximum free opening airflow velocity is given as 1.8m/s for Design RC 25 (Noise level). when looking at your velocities, it seems appropriate for the standard. In table-3, maximum recommended duct velocity for duct located...

Hello Carlo, Smoke can exit the duct and fill the shaft with smoke if you do not have damper. Moreover, the outside air duct is not smoke exhaust duct. Therefore, it is not allowed to use this duct as smoke exhaust system duct in fire condition. In fire scenario, outside fresh air may be...

Hello, In your fire scenario, you may need to prevent outdoor air coming to the floor when fire occurs. In that case, you will need damper at the fresh air duct. Moreover, shaft connects to four floors and if you don't have smoke dampers at the duct connecting to the floor, smoke may have...