GLYCOL SYSTEM PIPING GUIDE

CONSIDERATIONS AND INSTALLATION TIPS FOR GLYCOL DISTRIBUTION SYSTEMS

INTRODUCTION

Glycol is the lifeblood of a plant, and the piping is the veins and arteries that carry it to each point of use. While it is essential for a glycol system to function, piping is often overlooked during optimization projects, and it’s also one of the first project costs cut when an installation budget needs trimming. Piping material selection greatly impacts pressure drop, quality, and leak load. Whether you are installing a brand new system or considering upgrades to an existing one, this e-book will assist you in identifying the best piping materials for your application and give you installation and maintenance tips to give you the best performance possible.

It’s assumed you have already identified your system's pressure, flow, and quality requirements. If you are unsure, we strongly recommend that you contact us for help determining these parameters.

This guide should supplement any service manuals for your equipment or piping materials.

The pictures in this guide are presented only as examples. They do not necessarily show the best way to install your particular system.

If you need help, please consult a Tanktemp representative for expertise in installing your piping system.

PRESSURE DROP   

CONSIDERATIONS FOR REDUCING PRESSURE DROP

Pressure drop is the reduction in pressure from the chiller discharge to points-of-use. While it is best practice to reduce pressure drop as much as possible, eliminating it is impossible. A well-designed system should have a pressure drop of at most 10% from the chiller discharge to the farthest point in the distribution piping.

Pressure drops occur as the glycol travels to the point of use through pumps, filters, piping, and all fittings and valves in between. Any obstruction will result in a loss of pressure.

While a pressure drop is expected, excessive pressure drop can lead to poor system performance and higher energy consumption. Flow restrictions require higher system pressure to overcome the restriction, causing higher than necessary energy consumption and frictional heat. Every 2-psi increase or 1F decrease in temperature can cause approximately a 1% increase in power consumption. Since a glycol chiller system is often the highest electrical consumer in a plant, properly controlling pressure drop and temperature can offer significant savings opportunities.

When pressure drops at the point of use, the common reaction is to increase the pressure at the pump(s). Unfortunately, this does nothing to address the root cause of the pressure drop.

At higher pressures, leaks will leak more, and other forms of artificial demand will waste more chilling power and energy. Instead of turning up the pressure, look at your system and see why there is an issue.

For example, if you notice periods with intermittent demand, meaning periods when you need more cooling for a specific part, look at adding a dual-stage of your process chiller to your system so you’ll have extra BTU/Chilling power to supply that demand event.

If tanks are under-pressurized and showing stratification, check the size of the lines feeding the tanks. Many times facilities will add tanks as their process demand increases, but they never increase the size of the glycol lines or the chiller. Hoses are a great way to connect, however, have a high thermal loss and can often be undersized. These are common causes of pressure drop that can easily be fixed.

Finally, if you have chiller units that are short cycling—turning on and off often— this can be because they are not properly controlled. In this case, add a master controller that can monitor your system demand and select the most efficient combination to meet it. However, if the short cycling is due to insufficient piping or excessive pressure drop in the plumbing, addressing these issues first can provide significant operational benefits.

Calculate the pressure

To calculate the pressure in your glycol lines, you will need the elevation of the highest fixture (finding the difference between the elevation of the chiller/pump and our highest outlet). If your highest fixture is above your chiller pump, you will experience a loss in pressure. To account for this, you can expect to lose 0.5 PSI for every foot of elevation gain. However, if your highest fixture is below your chiller/pump, you will add 0.5 PSI for every foot of elevation drop.

Next, we must calculate our system's static pressure at the supply source. To get the real pressure, we need to take our reading and subtract the elevation of our highest outlet.  See the charts below for basic references.

COMMON PIPING MATERIALS

Choosing the right glycol distribution system is a large component of the glycol system energy costs and increasing plant efficiency. Here’s an overview of common piping materials and some considerations to consider when selecting a pipe for your installation.

Choose piping materials based on the glycol's operating temperature and pressure. Keep in mind that glycol can be contaminated with rust, air, algae, particulates, animals, products, and oil, to name a few. Therefore, the piping must not deteriorate in the presence of these contaminants.

Common piping materials include copper, brass, PEX, ABS, stainless steel, and PVC. PVC is the most commonly used material, and we recommend it. However, OSHA has stated that it is not safe for use in compressed air systems and we often see this.

Generally speaking, PVC, ABS, Brass, and copper would be the best choices since they are not prone to build-up and will provide years of low-pressure drop delivery. 

Stainless steel is not prone to build-up or leaks, but it is very expensive and only called for in specialty applications—if you need it, you’ll know.

MATERIALS

COPPER- RECOMMENDED FOR USE WITH GLYCOL AND STAINLESS TANKS. 

Copper piping can last 50 years and is the standard hard pipe in the plumbing industry. It can withstand high water pressure and temperatures. It comes in various grades of thickness, separated into two categories: rigid and flexible copper pipes.

A rigid copper pipe is typically used for water supply lines, whereas flexible copper pipes are used in tight spaces where the malleable copper can bend.

Copper will not rust, has a smooth interior, and promotes low-pressure drops. Quality installation and brazing or a press-fit system are required to prevent leaks. Copper pipes are corrosion-resistant, can handle high water pressure, and tolerate of hot and cold temperatures. 

Tanktemp offers this installation solution. Although the press fit system has higher material costs, labor costs can be lower. Tanktemp offers this solution

STAINLESS STEEL- RECOMMENDED FOR USE WITH GLYCOL AND STAINLESS TANKS. 

There is no rust and low-pressure drop with properly installed stainless. It is labor-intensive for both materials and installation. It is normally seen on the product side and rarely seen on the glycol side. However, it is costly and often difficult to install and repair. Tanktemp offers this solution

BRASS- RECOMMENDED FOR USE WITH GLYCOL AND STAINLESS TANKS. 

Brass will not rust, has a smooth interior, and promotes low-pressure drops. Tanktemp offers this installation solution and is our standard for tank fittings. Material costs can add up, but installation is faster and lasts longer than PVC or other materials. Tanktemp offers this solution

*Brass fittings are normally used by Tanktemp to connect plumbing to tanks. 

PVC- RECOMMENDED FOR USE WITH GLYCOL. PVC fittings are not recommended on tanks. 

PVC plumbing pipe is known for its versatility, lightweight build, and blockage resistance. PVC piping is generally used in all plumbing applications. It’s often used as a main supply and return pipe in most glycol installations. Sch80 is lightweight and inexpensive for parts and labor. PVC is easy to insulate and offers good R-values. Solutions in pre-insulated options as well. 

Sch40 is not recommended for Glycol. 

Sch80 is recommended for Glycol and is Tanktemp’s standard. Tanktemp offers this solution

*There are several manufacturers of PVC and insulated and non-insulated solutions. Not all are equal. 

ABS- RECOMMENDED FOR USE WITH GLYCOL. However ABS fittings are not recommended on tanks. 

ABS piping is a type of plastic piping similar to PVC and is distinguishable by its black color. Known for its long lifespan, ABS is used only for drain and waste piping. Glycol is not potable water, so ABS is the perfect material to choose from. Resistant to cold temperatures—Although its structure doesn’t hold the flexible properties of PVC, it can better withstand colder temperatures. Warps in warm temperatures—ABS pipes don’t survive long in direct sunlight and can warp under strong ultraviolet light.

Tanktemp offers this solution. 

PEX- RECOMMENDED FOR USE WITH GLYCOL. PEX fittings are not recommended on tanks.

PEX is an affordable plastic plumbing solution that can withstand hot and cold water and is commonly used for water supply lines.

Lightweight and inexpensive for parts and labor. PEX needs more support more often. Inside use only—Since PEX is susceptible to deterioration from ultraviolet rays, these pipes can’t be used outside.

Tanktemp offers this solution. 

HEAVY RUBBER HOSE- RECOMMENDED FOR USE WITH GLYCOL.  

It is not generally used as a header due to lower sizes, thermal loss, and being flexible and hard to support on a wall. Hose is not usually a long-term solution and is often replaced. Hose is an affordable plumbing solution that can withstand both hot and cold water and is commonly used for the final glycol supply and return lines to a tank. It is often seen used with portable chiller units. 

Lightweight and inexpensive for parts and labor. Hose needs more support more often. 

Inside use only—Since the hose is susceptible to deterioration from ultraviolet rays, these should not be used outside.

Tanktemp offers this solution. 

BLACK IRON - NOT RECOMMENDED. A common mistake we see in installs.

*NOT RECOMMENDED FOR USE WITH GLYCOL OR STAINLESS TANKS. Moderate material costs and easy sourcing, however, will cause rust in the in lines and promote contaminants in the system. Prone to deterioration, these pipes are more susceptible to rust and corrosion than other materials. Any rust in a glycol system can ruin not only the glycol chiller, but also the tanks. 

GALVANIZED IRON - NOT RECOMMENDED. A common mistake we see in installs. 

*NOT RECOMMENDED FOR USE WITH GLYCOL OR STAINLESS TANKS.  Moderate material costs and ease of source, however, will cause rust in the lines and promote contaminants in the system. Prone to deterioration: These pipes are more susceptible to rust and corrosion than newer pipes. Any rust in a glycol system can ruin not the glycol chiller, but also the tanks. 

THERMAL EXPANSION

All piping materials experience thermal expansion—some materials more than others. If thermal expansion and contraction are not compensated for in the system design, it can have long-term, damaging effects. Leaks from stressing threads, soldered points and compromised couplings are just a few examples of failure points.

For specific guidance, contact Tanktemp.

PLUMBING SIZING DESIGN  

Properly sizing your pipe for a glycol plumbing project will make a world of difference in the functionality of your system. Choosing the pipe size that can safely supply the volume of glycol needed throughout your system is critical to your plant's performance. 

To calculate the appropriate size for plumbing pipes, you must consider factors such as the flow rate and pressure of the glycol transported. Additionally, you'll need to factor in the distance the fluid travels and any restrictions or bends in the pipe.

Here's a basic process for calculating plumbing pipe size:

• Determine the flow rate: This is usually given in gallons per minute (GPM). The flow rate depends on your system's requirements and the fixtures/tanks or equipment it will supply.
• Calculate the required pipe diameter: The size of the pipe will depend on the flow rate and the acceptable pressure drop. You can use pipe sizing tables provided by plumbing codes or software programs designed for this purpose. These tables consider flow rate, pipe material, and pressure drop to determine the appropriate pipe size.
• Consider other factors: In addition to flow rate and pressure drop, you'll need to consider factors such as the weight of glycol/water transported, the material of the pipes (copper, PVC, etc.), and any regulations or codes that may apply to your specific situation.
• Consult a professional if needed: If you're unsure about the calculations or if your plumbing system is complex, it's a good idea to consult with a licensed plumber or engineer who can help ensure that your system is properly designed and installed.

We can offer more detailed guidance on calculating the appropriate pipe size by obtaining specific details about your plumbing project, such as the floor plan, number of tanks, size of the barrel rooms, flow rate, and intended use of the system.

Tanktemp glycol chillers have built-in pressure valves that maintain the pressure to all tanks when combined with the proper plumbing solutions. 

Flow is measured in gallons per minute (GPM). Your friction loss through a pipe is measured in pounds per square inch (PSI), and the velocity is measured in feet per second (FPS). Velocity is the rate of speed at which the glycol is traveling. The proper size mainline for your project will be the size closest to your flow rate without restricting it or exceeding the safe velocity.

Tank specs will often have flow specs they need on them or in the tank spec drawing for them to maintain cooling. Tanktemp can help you design the plumbing solution to feed all your equipment from the chiller. 

Many things will factor into the correct plumbing for your plant. To size the chiller/pumps, we’re going to need four key bits of information:

• Total tank units and their need GPM 
• Developed the length of the most remote outlet
• Elevation of the highest outlet
• Water pressure

AGING GLYCOL SYSTEMS-

Most glycol systems are or become a hybrid of new and old. In these cases, piping connections can be made simply by gluing two joints, flanged or threaded. However, we strongly suggest you have no iron in your system regarding chemical composition. Iron connected to stainless, brass, or copper can cause a chemical reaction called galvanic corrosion. Glycol will also eat the coating off galvanized fittings.

LEAKS  

COST OF LEAKS AND LEAK DETECTION

Glycol systems as they age have leaks. Regardless of the source, they can greatly reduce operating effectiveness and cost a lot in energy. The U.S. Department of Energy estimates that as much as 10%-30% of BTUs are lost to leaks and thermal loss - and it's higher in many plants.

Tanktemp recommends a post-installation leak check as well as periodic leak detection checks. Upon commissioning, the system can be checked for leaks by simply charging the system with air and then water before charging the system with glycol. If the pressure drops in lines, there are leaks.

We recommend annual leak audits to identify and fix leaks that develop over time.

The chart below shows how much even a single leak can cost you year after year. An annual leak detection plan can help you stay ahead of the game.

• A tiny drop of water can add up to 15 gallons a day
• A steam 1/32nd of an inch loses 25 gallons a day 
• A steam 1/16th of an inch loses 100 gallons a day 
• A stream 1/8th of an inch loses 400 gallons a day 
• A stream 1/4th of an inch loses 1,600 gallons a day

Connecting fittings- PVC into metal, never metal into PVC unless special reinforced female adapters are used. This is one of the most common places where leaks will occur.

When two different materials are combined, you have the opportunity for different rates of expansion and corrosion. 

Contact Tanktemp at ttinfo@tanktemp.com if you have any questions. 

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