Based on your question, I am going to make the assumption the GPC you have is funded with O&M appropriated funds and NOT nonappropriated funds (NAF).

Unfortunately, the answer is “it depends”.  It depends on the NAF Program Group (I through IV) being supported as well as the Category (A, B, or C) these MWR Facilities are (see example below).  There could also be other factors at your local, MAJCOM, or even Service Component Level; such as a waive that we would have no way of knowing about. 

Therefore we strongly recommend you consult with your local GPC AOPC and possibly your local contracts attorney-staff judge advocate to get a definitive answer applicable to your installation and the MWR facilities you are being asked to procure propane for.

If use of appropriated funds is authorized at your installation for these MWR facilities; at an absolute minimum, pre-purchase approval is required according to the Government charge card guidebook. "Pre-Purchase Approval: When required and identified by local procedures, documentation showing approvals for special-use items (hazardous material, information technology, etc.) before they are purchased."

References:

a) Department of Defense Government Charge Card Guidebook for Establishing and Managing Purchase, Travel, and Fuel Card Programs, Effective 1 October 2017.

b) DoD Instruction 1015.15, “Establishment, Management, and Control of Nonappropriated Fund Instrumentalities and Financial Management of Supporting Resources” (see enclosure 3 and 4).  Example:

    6.2.1.1.  Category A – Mission Sustaining Activities.  Category A activities have virtually no capacity for generating NAF revenues and are supported almost entirely with APFs.  The use of NAFs is limited to specific instances where APF support is prohibited by law or when NAF support is essential for the operation.

    6.2.1.2.  Category B – Basic Community Support Activities.  Category B activities are financed with a combination of NAF and APF resources.  Because their NAF revenue-generating capability is limited, these activities shall be substantially supported with APFs.

    6.2.1.3.  Category C – Revenue-Generating Activities.  Category C activities have the highest capability to generate NAF revenues and generally receive only indirect APF support, except as authorized by law.  Overseas activities are authorized limited direct APF support.  Military MWR and Armed Service Exchange Category C activities at designated remote and isolated locations are authorized funding under Category B rules…

c) DoD Instruction 1015.10, “Military Morale, Welfare, and Recreation (MWR) Programs,” July 6, 2009, as amended.

In the unlikely event you have a NAF funded purchase card; see DoDI 4105.67, it addresses NAF and purchase cards.