The Stanford Underwater Laboratory has designed two autonomous underwater pumping systems and one surface pumping system that were designed using off-the-shelf components and open source software for easy maintenance, service, and operation. There are several other pumping systems in the literature (Albright et al. 2013, Martin et al. 2004) and available on the market (KC Denmark Research Equipment, Mclane Research Laboratories, NOAA) that may be of interest to some researchers, we feel that our pumping systems bring the best of these systems together for a more complete package with ease of use and versatility for those doing coastal/shallow water research. The electronics controlling our pumping systems are Ardunio interfaces and software allowing the user the flexibility to modify/customize the provided base code as needed for their application. The relays, valves, pumps, manifolds, fittings, o-rings, and miscellaneous hardware are all off-the-shelf components that the user can easily purchase for spares or replacement parts. The pressure case is custom built, but is also made from off-the-shelf PVC however, the end caps are CNC machined and are a piston seal design. The pressure cases were designed for 30m working depths although the MG1 is limited to 20psi and is recommended for use under 14m water depth where the MG2 is usable to 30m.
Our second generation 12 port auto sampler uses ¼” pinch valves and a peristaltic pump to autonomously sample from one common port and deliver up to 12 ports. In this mode, the end user can attach bottles, bags, syringes, or nearly any container desired for sample acquisition or even a series of flow-through sensor. The MG1 uses a 220 ml min-1 peristaltic pump to flush and deliver water to each port. The current design can take up to four 8-pack D-cell 12VDC battery packs running in parallel, but the user could also install their own custom battery packs. The MG1 uses the Arduino Pro Mini and mechanical relays to control the pump and valves.
The third generation 12 port auto sampler uses the same components as the second generation, but it is plumbed and wired to work in reverse allowing the system to sample individually from 12 ports into 1 common port. This system is intended for working with flow-through sensors where it can sample up to 12 different sources and deliver it to one suite of flow-through instruments.
Our second generation autonomous 2 position pumping system was initially designed to be use for the BEAMS array developed by Takeshita et al. (2016). The MG2 pumping system uses two solenoids to control two Sea Bird Electronics 5M pumps although it can power any 12VDC external component. However, this design can power more than just external pumps, it can power any 12VDC component and the added bonus is that more channels can be added with corresponding external electrical connections and devices. Our current design can take six 8-pack D-cell 12VDC battery packs running in parallel, but custom battery packs could be used. The typical BEAMS array cycles the SBE 5M pumps about every 15 minutes and during this time the selected SBE 5M pump runs continuously consuming approximately one battery pack/week, so this system has a battery lifespan of about 6 wks. Like our other systems it also uses an Arduino Pro Mini and mechanical relays to control the external devices.
This system has been used in the field since 2012 and has been published in several articles (Teneva et al. 2013, Koweek et al. 2014, Koweek et al. 2015, Koweek et al. 2016) and we are presently using in in our Kelp Forest project. The earlier version was controlled by LabView software, version 2 uses an Arduino Mega to control a solenoid bank that powers pneumatic controlled valves. The system is versatile and the number of valves is only limited to the I/Os on the Arduino Mega. This system can be run in autonomous mode or for real-time monitoring. Like our other systems the software is open source and can be easily customized as needed.
We can work with the customer to design a different pressure case if more or less battery life is required or if there is a need for a different diameter pressure case (limitations may apply). Adding more channels to MG2 is possible, but cost depends on factors such as the number of channels, length of cables and bulkhead connectors, and the number of SBE 5M or 5P pumps.