അറ്റ്മോസ്ഫിയർ (യൂണിറ്റ്)
ദൃശ്യരൂപം
(Atmosphere (unit) എന്ന താളിൽ നിന്നും തിരിച്ചുവിട്ടതു പ്രകാരം)
അറ്റ്മോസ്ഫിയർ (യൂണിറ്റ്) പ്രമാണ അറ്റ്മോസ്ഫിയർ (ചിഹ്നം: atm) മർദ്ദത്തിന്റെ ഏകകമാണ്. ഇത് 101 325 Pa (1.013 25 bar) എന്ന് നിർണയിച്ചിരിക്കുന്നു. ചിലപ്പോൾ ഇതിനെ അവലംബമായോ പ്രമാണിക മർദ്ദമായോ ഉപയോഗിക്കുന്നു.
ചരിത്രം
[തിരുത്തുക]മർദ്ദ ഏകകങ്ങളും സമമൂല്യങ്ങളും
[തിരുത്തുക]പാസ്കൽ | Bar | Technical atmosphere | Standard atmosphere | Torr | Pounds per square inch | |
---|---|---|---|---|---|---|
(Pa) | (bar) | (at) | (atm) | (Torr) | (psi) | |
1 Pa | ≡ 1 N/m2 | 10−5 | 1.0197×10−5 | 9.8692×10−6 | 7.5006×10−3 | 1.450377×10−4 |
1 bar | 105 | ≡ 100 kPa
≡ 106 dyn/cm2 |
1.0197 | 0.98692 | 750.06 | 14.50377 |
1 at | 0.980665×105 | 0.980665 | ≡ 1 kp/cm2 | 0.9678411 | 735.5592 | 14.22334 |
1 atm | 1.01325×105 | 1.01325 | 1.0332 | 1 | ≡ 760 | 14.69595 |
1 Torr | 133.3224 | 1.333224×10−3 | 1.359551×10−3 | 1.315789×10−3 | ≡ 1/760 atm
≈ 1 mmHg |
1.933678×10−2 |
1 psi | 6.8948×103 | 6.8948×10−2 | 7.03069×10−2 | 6.8046×10−2 | 51.71493 | ≡ 1 lbF /in2 |
A pressure of 1 atm can also be stated as:
- ≡1.01325 bar
- ≡ 101325 pascal (Pa) or 101.325 kilopascal (kPa)
- ≡ 1013.25 millibars (mbar, also mb)
- ≡ 760 torr[n 1]
- ≈ 760.001 mm-Hg, 0 °C, subject to revision as more precise measurements of mercury’s density become available[n 2][n 3]
- ≈ 29.9213 in-Hg, 0 °C, subject to revision as more precise measurements of mercury’s density become available[n 3]
- ≈ 1.033 227 452 799 886 kgf/cm²
- ≈ 1.033 227 452 799 886 technical atmosphere
- ≈ 1033.227 452 799 886 cm–H2O, 4 °C[n 2]
- ≈ 406.782 461 732 2385 in–H2O, 4 °C[n 2]
- ≈ 14.695 948 775 5134 pounds-force per square inch (psi)
- ≈ 2116.216 623 673 94 pounds-force per square foot (psf)
- = 1 ata. The ata unit is used in place of atm to indicate that the pressure shown is the total ambient pressure on the system being calculated or measured.[1] For example, for underwater pressures a pressure of 3.1 ata would mean that the 1 atm of the air above water is included in this value.
- Notes:
- ↑ Torr and mm-Hg, 0°C are often taken to be identical. For most practical purposes (to 5 significant digits), they are interchangeable.
- ↑ 2.0 2.1 2.2 This is the customarily accepted value for cm–H2O, 4 °C. It is precisely the product of 1 kg-force per square centimeter (one technical atmosphere) times 1.013 25 (bar/atmosphere) divided by 0.980 665 (one gram-force). It is not accepted practice to define the value for water column based on a true physical realization of water (which would be 99.997 495% of this value because the true maximum density of Vienna Standard Mean Ocean Water is 0.999 974 95 kg/l at 3.984 °C). Also, this “physical realization” would still ignore the 8.285 cm–H2O reduction that would actually occur in a true physical realization due to the vapor pressure over water at 3.984 °C.
- ↑ 3.0 3.1 NIST value of 13.595 078(5) g/ml assumed for the density of Hg at 0 °C
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[തിരുത്തുക]- ↑ Scuba Diving & Other Fun Activities, The Difference Between An ATM & An ATA