ঘর, মোটেল, হোটেল বা বাণিজ্যিক যেকোন ভবনের জন্য ঝরনা, রান্নাঘর, বাথরুম, ওয়াশিং মেশিন, ডিশ ওয়াশার এবং অন্যান্য যন্ত্রপাতিগুলির জন্য পর্যাপ্ত গরম পানির প্রয়োজন। ভবনের ব্যাবহারকারী অনুসারে পর্যাপ্ত পরিমাণ গরম পানির সাপ্লাই থাকতে হবে, এজন্য ভবনে যেন পর্যাপ্ত পরিমান গরম পানির সাপ্লাই থাকে সেজন্য গরম পানি স্টোরেজ এর ডিজাইন করতে হবে। প্রপার ডিজাইন না করা হলে পানির অপচয় হতে পারে কিংবা পানির শর্টেজ হতে পারে, তাই পরিমিত গরম পানির পরিমান এস্টিমেট করা খুবই প্রয়োজনীয়।
প্রয়জনীয় কোড/রেফারেন্সঃ
*American Society of Heating, Refrigeration and Air Conditioning Engineers ASHRAE 2003 Applications Handbook
*The Uniform Plumbing Code (UPC)
*The American Society of Plumbing Engineers (ASPE) handbooks.
গুরুত্বপূর্ণ টার্মঃ
1. Fixture – A device for the distribution and use of water in a building. Example: shower, urinal, fountain, shower, sink, water faucet, tap, hose bibs, hydrant etc.
2. Maximum Possible Flow –The flow that occurs when all fixtures are opened simultaneously. Since most plumbing fixtures are used intermittently and the time in operation is relatively small, it is not necessary to design for the maximum possible load.
3. Maximum Probable Flow –The flow that occurs under peak conditions for the fixtures that are expected to be in use simultaneously and NOT the total combined flow with all fixtures wide open at the same time. The probability that all fixtures will be used in a building at the same moment is quite remote. Generally, as the number of fixtures increases, the probability of their simultaneous use decreases. The plumbing system is normally designed on probability theory. If pipe sizes are calculated assuming all taps are open simultaneously, the heater size and the pipe diameters will be prohibitively large, economically unviable and unnecessary. Maximum probable flow is also referred to as “peak demand” or “maximum expected flow”.
4. Intermittent Demand – Plumbing fixtures that draw water for relatively short periods of time are considered an intermittent demand. The examples include bathroom fixtures, kitchen sinks, laundry trays and washing machines. Each fixture has its own singular loading effect on the system, which is determined by the rate of water supply required, the duration of each use, and the frequency of use.
METHODS OF ESTIMATING HOT WATER DEMAND
There are four types of method to estimating hot water demand.
Method-1: Estimating Hot Water Demand on Fixture Units.
Method-2: Estimating Hot Water Demand on Fixture Types.
Method-3: Estimating Hot Water Demand on Occupants/Units.
Method-4: Estimating Hot Water Demand on Daily Use.
Method-2:
Estimating Hot Water Demand on Fixture Types.
If a particular fixture or a specific building type is not listed above, the flow rate can be assigned based on engineering judgment, best practices historical data, or supplier’s instructions.
Notes:
1. Note1: A Demand Factor is applied to calculate the Maximum Probable Demand, which is the rate at which the heater will generate hot water and is also termed as “the recovery rate or heater capacity”. A high demand factor will mean a higher recovery rate or heater size.
2. Note2: The storage volume of the tank needs adjustment for usable volume to account for the drop in temperature resulting from withdrawal of hot water and continuous entry of cold water in storage tank. The “maximum probable demand” is thus factored by the “storage capacity factor” to determine the “storage tank capacity”.
একটি এপার্টমেন্ট বিল্ডিং এর এস্টিমেট:
Determine the heater and storage tank size for an Apartment Building having the following fixtures.
Solution:
At first estimate possible maximum demand.
From table above, for apartment building hot water demand as per types of fixture,
AUTHOR:
Md. Johirul Islam Raju
Engineer, Plumbing design & installation.
CBT&A Certified Assessor (Plumbing),Bangladesh Technical Education Board (BTEB).
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