We present an analysis of X-ray high quality grating spectra of the Seyfert 1 galaxy NGC 5548 using archival Chandra -HETGS and LETGS observations for a total exposure time of 800 ks .
The continuum emission ( between 0.2-8 keV ) is well represented by a power law ( \Gamma = 1.6 ) plus a black-body component ( kT = 0.1 keV ) .
We find that the well known X-ray warm absorber in this source consists of two different outflow velocity systems .
One absorbing system has a velocity of - 1110 \pm { 150 } km s ^ { -1 } and the other of - 490 \pm { 150 } km s ^ { -1 } .
Recognizing the presence of these kinematically distinct components allows each system to be fitted independently , each with two absorption components with different ionization levels .
The high velocity system consists of a component with temperature of 2.7 \pm 0.6 \times 10 ^ { 6 } K , \log U = 1.23 and another component with temperature of 5.8 \pm 1.0 \times 10 ^ { 5 } K , \log U = 0.67 .
The high-velocity , high-ionization component produces absorption by charge states Fe xxi-xxiv , while the high-velocity , low-ionization component produces absorption by Ne ix-x , Fe xvii-xx , O vii-viii .
The low-velocity system required also two absorbing components , one with temperature of 5.8 \pm 0.8 \times 10 ^ { 5 } K , \log U = 0.67 , producing absorption by Ne ix-x , Fe xvii-xx , O vii-viii .
The other with lower temperature ( 3.5 \pm 0.35 \times 10 ^ { 4 } K ) , and lower ionization ( \log U = -0.49 ) ; producing absorption by O vi-vii and the Fe vii-xii M-shell UTA .
Once these components are considered , the data do not require any further absorbers .
In particular , a model consisting of a continuous radial range of ionization structures ( as suggested by a previous analysis ) is not required .

The two absorbing components in each velocity system are in pressure equilibrium with each other .
This suggests that each velocity system consists of a multi-phase medium .
This is the first time that different outflow velocity systems have been modelled independently in the X-ray band for this source .
The kinematic components and column densities found from the X-rays are in agreement with the main kinematic components found in the UV absorber .
This supports the idea that the UV and X-ray absorbing gas is part of the same phenomenon .
NGC 5548 can now be seen to fit in a pattern established for other warm absorbers : 2 or 3 discrete phases in pressure equilibrium .
There are no remaining cases of a well studied warm absorber in which a model consisting of a multi-phase medium is not viable .