Setting aside all the negativity (most of it relatively justifiable, even if absurd sounding, and most of it also relatively work-around-able):
- Bricking all the pumps at once (I assume this is being done before/after hours, and there IS a recovery procedure)
- Networking creating sparks that blow the place up (How is hooking up 2 cables to 2 pumps different than hooking up 1 cable to 1 pump)
- Interrupting customers (Again, before/after business hours, or during non-peak hours, and only doing a few at a time)
- Simultaneous hacking exposure (Connecting device doesn't have to be internet-connected, and in that case, how is connecting to one a time different than connecting to all of them)
- Automating yourself out of a job/hourly pay (Nothing wrong with working smarter, rather than harder; applies to just about every career, even with an hourly wage)
Run your virtualization hypervisor of choice (VMware ESXi or VMware Workstation, VirtualBox, whatever), and install your vendor's preferred OS and software application as a VM. Clone it many, many times (as many times as you have NIC ports). Give each one of them a single dedicated NIC. Run cables to each pump, and start your engines (that's about as close as I can come to making a gas station pun).
It's a fairly simple solution in that it doesn't require any fancy networking knowledge (VLANs, iptables, NATting, etc), and you're using a very straightforward virtualization configuration that most vendors will agree is supportable (their preferred OS, a single network port, etc).
If you can find a way to setup a couple of quad port NICs on your laptop, you could probably use that as well. In fact, many laptops have the option of purchasing a "docking station" that often have PCIe slots. If that's the case, maybe that's all you need to make the above solution work.
I think that being able to do "4 or 8 at a time", using a solution like this one, would be a huge improvement over doing 8 or 16 of them "one at a time".