(redirected from permeances)
Also found in: Dictionary.


The reciprocal of reluctance in a magnetic circuit. It is the analog of conductance (the reciprocal of resistance) in an electric circuit, and is given by

Eq. (1), where B is the magnetic flux density, H is the magnetic field strength, and the integrals are respectively over a cross section of the circuit and around a path within it.

From Eq. (1), it can be shown that Eq. (2) is valid, where A

is the cross-sectional area of the magnetic circuit, l its length, and μ the permeability. If the material is ferromagnetic, as is often the case, then μ is not constant but varies with the flux density and the complete magnetization curve of B against H may have to be used to determine the permeance. See Reluctance


A characteristic of a portion of a magnetic circuit, equal to magnetic flux divided by magnetomotive force; the reciprocal of reluctance. Symbolized P.


A measure of a material’s resistance to water-vapor transmission, expressed in perms. Equal to the ratio of (a) the rate of water vapor transmission through a material or assembly between its two parallel surfaces to (b) the vapor pressure differential between the surfaces.
References in periodicals archive ?
Table 1: Gas permeance of seeded membrane without intermediate layer Synthesis time Permeance (mol/[m.
Table 3: Gas permeance results of as-synthesized membrane with boehmite layer Synthesis time Permeance (mol/[m.
1998) expressed the permeances of pure propane, n-butane, n-pentane, and n-hexane for a typical PDMS composite membrane with the following equation:
By using Equation (4), it is possible to calculate the permeances on the basis of Free Volume Model for a vapour--permanent gas mixture.
For vapour-selective membrane materials, the permeances for a vapour--permanent gas mixtures strongly depend on the temperature and feed composition (Pinnau and He (2004) and Jiang and Kumar (2005)).
The selectivity and permeance of hydrogen gas is encouraging using cosolvent THF in sample 20PT-3 and 20PT-3-30s as stated in Table 3.
2] Type of permeance Membrane membrane Cosolvent (GPU) PDMS/PES Flat sheet None 1750.
4] permeances increased significantly for casting solution including higher concentration of BuOH (Fig.
2] permeances of gas mixture are significantly higher than those of pure gas at similar operating conditions.
Although in facilitated transport membrane, the error in thickness measurement is more much oblivious than other type of membrane due to gel penetration into support pores and Solvent loss, the separation results presented in permeance to omit the error of thickness measurements.
2] permeance at same pressure for mentioned membrane was 0.
The common unit of permeance is GPU and 1 GPU is equal to 1 x [10.