Both industrial and municipal waste water system owners are moving more towards sourcing complete pumping systems rather than having contractors purchase the individual components and then assembling and designing the systems. By outsourcing complete systems it creates a more reliable, more cost effective system. Also the pump system supplier is responsible for the promised performance, up-time and service to the owner for the system’s lifetime.
Contractors also benefit with predesigned systems in which they do not have to understand the complete system to install and start-up the system. A good system is designed such that the system is factory tested and delivered to the site. The contractor with most systems will only need to connect the input and output piping and electrical connections to the system. When needed factory personnel can be on hand to assist in start-up and training of system operability.
A service agreement for complete packaged pumping systems can be purchased by the owner so that the supplier will periodically visit and perform necessary maintenance on the system and fine tune any programming requests by the owner. By having a service agreement with the manufacturer the owner can focus on running their facility rather than dealing with a pumping system’s performance .
In waste water typical systems provided would be for flocculants, sodium hypochlorite, sodium bisulfite, ferric chloride and other chemicals. Ideally the pumps utilized in these systems should have safety devices to insure that if a hose or tube breaks in the pumps then the pumps affected would be shut down automatically. The Larox Flowsys pumps pictured above incorporate two hastelloy C probes in the pump heads which will sense liquid from a tube leak usually within a few seconds to shut the pumps down on a tube breakage. This insures that expensive polymers or aggressive chemicals are not continuously leaked to the external environment. Also the system is built upon a collection basin which will capture any undesirable chemical release.
Selection of the correct pump for pumping chemicals such as flocculants is very important. For instance gear pumps have a tendency to shear valuable flocculants and cause the flocculants to become less effective. In this case the owner may need to use twice as much of the required flocculants to perform the intended function. In that case the owner would spend thousands more per year on flocculants. A peristaltic pump is ideal for flocculants because it is a low shear device. So it is very gentle and does not damage costly flocculants. Thus less flocculants can be used per year and savings can be achieved.
Sodium hypochlorite is another chemical where the correct pump must be selected. In many facilities mechanical diaphragm pumps are used to deliver 12.5% sodium hypochlorite. However on warm summer days these pumps may experience vacuum degassing due to their design. This creates a situation where unexpected and unwanted time must be spent to get the pumps running again. A peristaltic pump is ideal for pumping sodium hypochlorite because the rubber hose is the only component in contact with the sodium hypochlorite. Also a peristaltic pump will not vacuum degas.
There are tube pumps and rubber hose peristaltic pumps. Tube pumps utilize thermoplastic tube materials such as Norprene or Tygothane. Peristaltic pumps that have these thermoplastic tubes typically do not utilize glycerin for lubrication or heat dissipation. In many cases, peristaltic pumps that use thermoplastic tubing are relatively small diameter pumps that have limited pumping discharge pressures of about 30 – 125 psig, depending on manufacturer and tube material.
Rubber hoses in peristaltic pumps typically have burst pressures that exceed 600 psig and have continuous pumping pressure capabilities up to 150 psig or greater. Peristaltic pumps with rubber hoses typically do utilize glycerin for either lubrication or heat dissipation or both. The lifetime of rubber hoses in most pumping applications far exceeds the tube lifetime that peristaltic pumps can achieve with thermoplastic tubes. Hose lifetime can be 5 – 10 times longer with a rubber hose compared to a thermoplastic tube.
There are many reasons for this variation. The number one factor that determines how long a hose or tube will survive is how many times the hose or tube is compressed. A common misconception that consumers typically have is that the largest determining factor of hose life is the medium that passes through the pump. However, this is not reality because it is much more relevant to concentrate on the number of times the hose or tube is compressed. Hose pump designs date back more than 75 years. Obviously tube and hose manufacturers have made monumental improvements over the past 75 years in rubber and elastomer technologies. You are wise to select the hose pump that places the least amount of compressions on the hose or tube.
Many hose pump manufacturers utilize two rubbing shoes or two rollers to compress the hose two times every 360 degree revolution. Newer designs utilize an eccentric shaft and roller that compress the tube or hose only once per 360 degree revolution. Single compression per revolution devices will produce at the very minimum twice the hose life than shoe designs and two or more rollers. Because the single roller design creates less friction and heat, the life of its hose or tube is often 4 – 5 times longer than two or more shoe or multiple roller designs. The savings in maintenance and operational costs of a single roller design compared to two or more shoe or roller designs is often just as much as the cost of new pump every year. So when choosing a peristaltic pump chose wisely. Operation and maintenance costs can vary widely from one manufacturer and designs to another.
In general the maintenance on peristaltic pumps is extremely easy. In 99% of instances the maintenance required is simply replacing a failed tube or hose. This process usually takes less than one hour to complete and in some designs only minutes.
As stated above there are some very good reasons to consider peristaltic pumps for many waste water applications. As well complete pumping systems designed and delivered by the pump manufacture create a very strong advantage for the owner and the contractor in waste water systems. Finally service contracts are an excellent way to guarantee pump system performance for the lifetime of the equipment.