പ്രധാന മെനു തുറക്കുക

അറ്റ്മോസ്ഫിയർ (യൂണിറ്റ്) പ്രമാണ അറ്റ്മോസ്ഫിയർ (ചിഹ്നം: atm) മർദ്ദത്തിന്റെ ഏകകമാണ്. ഇത് 101 325 Pa (1.013 25 bar) എന്ന് നിർണയിച്ചിരിക്കുന്നു. ചിലപ്പോൾ ഇതിനെ അവലംബമായോ പ്രമാണിക മർദ്ദമായോ ഉപയോഗിക്കുന്നു.

ചരിത്രംതിരുത്തുക

മർദ്ദ ഏകകങ്ങളും സമമൂല്യങ്ങളുംതിരുത്തുക

Pressure units
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:
  1. Torr and mm-Hg, 0°C are often taken to be identical. For most practical purposes (to 5 significant digits), they are interchangeable.
  2. 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. 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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  1. Scuba Diving & Other Fun Activities, The Difference Between An ATM & An ATA