What Is A Grease Trap In A Restaurant?
A grease trap, also known as a grease interceptor, is a plumbing device designed to intercept most greases and solids before they enter a wastewater disposal system. In restaurants, these devices are crucial for preventing fats, oils, and grease (FOG) from entering and clogging municipal sewer systems.
Grease traps work by slowing down the flow of warm or hot greasy water, allowing it to cool. As the water cools, the grease and oil separate from the water and float to the top of the trap, while the cooler water continues to flow through to the sewer system. This separation and retention of FOG not only protect the public sewer system but also help restaurants comply with local health and environmental regulations.
Types Of Grease Traps
1. Passive Hydromechanical (Manual) Grease Traps
Passive hydromechanical grease traps, also known as manual grease traps, are the most common type found in small to medium-sized food service establishments. These traps rely on gravity and the separation of grease from water based on their different densities. They typically have a capacity of 50 to 1,000 gallons and are installed under sinks or in-ground outside the building. Manual grease traps require regular cleaning and maintenance, usually every 1-3 months, depending on usage and local regulations.
2. Automatic Grease Traps
Automatic grease traps, or grease removal devices (GRDs), use a skimming mechanism to automatically remove accumulated grease and transfer it to a separate container. These systems are more efficient than manual traps and require less frequent maintenance. They often incorporate heating elements to keep the grease in a liquid state for easier removal. Automatic grease traps are ideal for restaurants with high-volume kitchens or limited space, as they can handle larger amounts of wastewater and FOG while occupying a smaller footprint.
3. Gravity Grease Traps
Gravity grease traps, also called large-capacity grease interceptors, are typically used in larger restaurants or food processing facilities. These traps are usually installed underground outside the building and can hold 1,000 to 100,000 gallons or more. They work on the same principle as passive hydromechanical traps but on a much larger scale. Gravity grease traps are highly effective at separating and storing large volumes of FOG, requiring less frequent cleaning (usually every 3-6 months) compared to smaller traps.
Important Parts Of Grease Traps
A. Flow Rate Controller
The flow rate controller is a critical component of a grease trap that regulates the speed at which wastewater enters the trap. By controlling the flow rate, it ensures that the water moves slowly enough through the trap to allow proper separation of grease and solids from the water. This component helps maintain the trap’s efficiency and prevents overloading, which could lead to grease escaping into the sewer system.
B. Inlet Pipe
The inlet pipe is where wastewater from the kitchen enters the grease trap. It’s typically designed to direct the incoming flow downward, which helps to reduce turbulence and promote the separation of grease from water. The inlet pipe often includes a flow control device to maintain the optimal flow rate for efficient grease separation.
C. Baffles
Baffles are internal walls or barriers within the grease trap that help to separate and retain grease while allowing water to flow through. They create separate compartments within the trap, slowing down the water flow and providing more time for grease and solids to separate from the water. Baffles also help prevent the escape of already trapped grease during periods of high water flow.
D. Outlet Pipe
The outlet pipe is where the treated water exits the grease trap and flows into the sewer system. It’s typically located at the opposite end of the trap from the inlet pipe and is designed to draw water from below the grease layer. This ensures that only the cleaner water at the bottom of the trap is discharged, while the grease and solids remain trapped.
How Do Grease Traps Work?
Grease traps work by exploiting the difference in density between water and fats, oils, and grease (FOG). As wastewater enters the trap, it’s slowed down by baffles and the trap’s design. This allows time for the water to cool, causing the lighter FOG to separate and float to the surface. Solids, being heavier, sink to the bottom. The cleaner water in the middle layer is then allowed to flow out through the outlet pipe. Over time, the layers of grease at the top and solids at the bottom accumulate, requiring periodic cleaning to maintain the trap’s efficiency. The grease trap cleaning frequency depends on the size and type of the grease interceptor. It’s generally a good idea to get your traps cleaned every 1-3 months because if ignored for too long, grease traps start smelling like rotting eggs, sewage, and spoiled meat.
How Much Does A Restaurant Grease Trap Cost?
The cost of a restaurant grease trap can vary widely depending on size, type, and installation requirements. Small, under-sink passive traps can cost between $500 to $2,000. Medium-sized traps (500-1,000 gallons) typically range from $5,000 to $12,000. Large, in-ground gravity interceptors can cost anywhere from $15,000 to $30,000 or more.
Automatic grease removal devices generally fall in the $5,000 to $25,000 range. These prices usually include installation, but it’s important to factor in ongoing maintenance costs, which can range from $200 to $800 per cleaning, depending on the trap’s size and accessibility.
How Big Of A Grease Trap Do I Need?
The size of the grease trap needed depends on various factors, including the restaurant’s size, type of food served, and local regulations. A general rule of thumb is to calculate the total volume of fixtures that discharge into the grease trap and multiply it by a retention time factor. Here’s a basic sizing table:
| Total Flow Rate (GPM) | Retention Time (minutes) | Grease Trap Size (gallons) |
|---|---|---|
| Up to 20 | 1 | 20 |
| 21-35 | 2 | 40-70 |
| 36-50 | 2 | 72-100 |
| 51-100 | 3 | 150-300 |
Who Installs Grease Traps?
In Texas, Grease traps or grease interceptors are typically installed by Licensed Master Plumbers. These professionals have the expertise to properly size, install, and connect grease traps to ensure they meet local codes and function effectively. If you’re looking for a grease interceptor installation company in Houston, TX Hydrojet is an excellent choice. We specialize in Houston grease trap cleaning as well as installations and provide high-quality service to ensure your restaurant complies with local regulations and maintains efficient kitchen operations. Our team of experienced plumbers can handle everything from initial assessment and sizing to installation and maintenance guidance.
