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molbloc, molbloc-S, molbox, molstic and molstic-s are trademarks, registered and otherwise, of 

DH Instruments, Inc. 

VCR is a registered trademark of the Swagelok Company.

 

Document 560056 

041215 

DH Instruments, Inc. 

4765 East Beautiful Lane 

Phoenix  AZ  85044-5318 

USA 

 

 

Tel 602.431.9100

Fax 602.431.9559

[email protected]

www.dhinstruments.com

 

 

 

Installation of 1/2 in. Filter Kit  

P/N 401888  

Instruction Sheet

 

This kit is used to provide filtration for 1/2 in. molbloc 
flowpaths, especially for 1/2 in. molstic-S and molbloc-
S installations.  Unlike most DHI molstics, the1/2 in. 
molstic-S does not include a filter because 
contamination is not a likely problem for the larger 
diameter molbloc-S elements that are normally 
installed on it.  For customers who expect the 
presence of significant particulate contamination, or 
want to maintain very clean gas, this 1/2 in. filter kit 
can be installed upstream of critical molstic-S 
components.  The kit may also be used for extra 
filtration on 1/2 in. supply lines to other molstics. 

INSTALLATION OF 1/2 IN. FILTER KIT 

ONTO 1/2 IN. MOLSTIC-S                      

(SINGLE OR DUAL) 

The filter kit can be installed on the upstream side of a 
single or dual channel 1/2 in. molstic-S.  If there is no 
regulator installed on the molstic-S, the filter will fit 
completely over the molstic base. 

If there is a regulator installed on the molstic-S, the filter 
kit should generally be installed upstream of the 
regulator.  In this installation, the filter will extend beyond 
the upstream side of the molstic.  If this is inconvenient, 
the filter kit can be installed on a supply line upstream of 
the molstic instead.

   

 

Figure 1.  

Dual

 

1/2 in. molstic-S, with 1/2 in. Filter Kit 

 

 

To 

permanently

 install the filter kit: 

  Using a pair of properly sized wrenches, remove the 

VCR x tube adaptor that is on the inlet end of the 
molstic-S.  This will leave a female VCR swivel nut 
(5) as the molstic interface.  Retain the tube adaptor 
for future use.  The VCR gaskets used in this 
connection are for one-time use and should 
therefore be discarded. 

  Place a new VCR gasket securely against the 

sealing surface inside the female VCR swivel nut . 

  Align the filter downstream fitting (4) in the VCR nut 

(5) and thread the nut onto the fitting by hand.  The 
filter should be installed with the printed arrow 
pointing in the direction of the gas flow. 

  Using two wrenches, tighten the filter’s downstream 

male VCR connector (4) into the female nut (5) 1/8 
turn past finger-tight. 

  Thread the 8VCR female coupling (2) onto the filter 

upstream connector (3).  Place a new VCR gasket 
securely against the sealing surface of the filter 
upstream fitting inside the 8VCR female coupling. 

  Thread the VCR x tube adaptor fitting (1) from the 

original molstic inlet into the 8VCR female coupling 
(2).  The coupling should be threaded onto both 
male fittings so that the VCR gasket is centered in 
the coupling.

 

  Using two wrenches, tighten the two male nuts from 

the tube adaptor (1) and filter upstream fitting (3) 
against each other in the coupling.  The connection 
should be tightened 1/8 turn past finger-tight. 

To 

temporarily

 install the filter kit: 

  Using a pair of properly sized wrenches, remove the 

VCR x tube adaptor that is on the inlet end of the 
molstic-S.  This will leave a female VCR swivel nut 
(5) as the molstic interface.  Retain the adaptor for 
future use.  The VCR gaskets used in this 
connection are for one-time use and should 
therefore be discarded. 

  Place a new 8VCR o-ring securely against the 

sealing surface inside the female VCR swivel nut. 

 

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