Abstract: A plurality of filter boxes which hold chemical filters include: a first filter box having a frame which holds a chemical filter and which has a guide groove provided on a side surface of the frame; and a second filter box having a frame which holds a chemical filter and which has a guide groove provided on a side surface of the frame; wherein the guide groove of the first filter box and the guide groove of the second filter box are different from each other at least in one of a width and a depth thereof. A plurality of filters can be installed or exchanged efficiently or in such a manner that the filters are positioned easily.

Abstract: A filter apparatus which holds a chemical filter includes a frame which holds the chemical filter and which has a guide groove provided on a side surface of the frame; and a casing which accommodates the frame. The guide groove has a first groove which is communicated with a back surface of the frame, and a second groove which is communicated with the first groove and which extends from a front surface of the frame toward an upper end thereof. The casing has a shaft member which is engageable with the first groove to support the frame and which is engageable with the second groove to release the frame from being supported. It is possible to install the filter efficiently so that the filter can be positioned with ease, and to unload the filter efficiently.

Abstract: A filter holding apparatus holding a first chemical filter and a second chemical filter, includes a first frame which holds the first chemical filter and which has a first guide groove provided on a side surface of the first frame; a second frame which holds the second chemical filter and which has a second guide groove provided on a side surface of the second frame and which is arranged while being overlapped with the first frame; and each of the first and second guide grooves has a first groove which is communicated with a back surface of one of the first and second frames, and a second groove which is communicated with the first groove and which extends toward an upper end of one of the first and second frames; wherein a distance between the second groove and the back surface in the first frame is different from a distance between the second groove and the back surface in the second frame.

Abstract: A filter box which holds a chemical filter includes a box-shaped frame which holds the chemical filter and a guide groove which is provided on a side surface of the frame. The guide groove includes a first recess which is arranged between an upper end and a lower end of the side surface of the frame and which is communicated with a side end of the side surface; and a second recess which is communicated with the first recess and which extends toward the upper end of the frame. With the guide grooves, it is possible to exchange the filter efficiently and with high positioning precision.