How to Select the Correct Pump Station
What is a pump station?
Pump stations typically fall into two categories, surface water and sewage. Both pumping stations are typically chambers with automatic pumps inside to move water from a lower elevation a higher mains drainage system when gravity flow is not an option.
Surface water stations are designed for handling water with no suspended particles or solids such as rainwater or collecting water from a basement conversion. Sewage stations are designed for handling solid sewage waste.
What is a sump pump?
Sump pumps are typically electrically powered automatic pumps that sit inside a chamber to move collected from the pump station chamber to the mains drainage.
Water booster pumps come in all shapes and sizes, from single pump systems that fit neatly into washrooms, attics, and cellars. Through to large triple pump systems aimed at commercial or industrial application. Due to the large amount of options on the market it can be pretty overwhelming when trying to understand what unit is right for your application. Before we look at how to choose a water booster pump, you need to understand why you have low water pressure in your home and how a booster pump works.
Basic Terminology
Below is a list of common terms that you will need to understand as you will often see find these when selecting a pump station: –
- Head – The amount of vertical lift from the bottom of the chamber to the sewer.
- Pumping Main – This is the main pipe from the tank to the sewer.
- Solid Handling – The pump capacity to handle suspended particles in the water.
- Flow Rate – The amount of water passing through the pump in litres per second.
- Frictional Losses – Forces that occur on the fluid over a set distance
- Self-Cleansing Velocity – Velocity of waste needed to prevent excess friction in the pumping main.
How do you Calculate a Pump Station?
All pumps operate at peak performance when running at the centre of the pump curve. An example of this is shown below but you will need to check your individual pump technical specification for your curve details pump curves.
To calculate – Take the overall lift and then for every 10m horizontal add another 0.5m to the lift.
e.g.: you have a run of 30m with a lift of 1.5m, this equates to 3.0m overall dynamic lift. Then look at the pump curve at 3m lift and see the flow. see the pump curve chart example below. If your overall lift surpasses the 5m, you need to move up to a higher head pump.
Often, people may choose to opt for a higher specification pump than is required under the impression that they are future-proofing themselves against pump failure or poor performance. This is a mistake as too much suction will place excess pressure on the pump, and it will quickly burn out.
Guide To Sizing A System
1. Determine the application the pump is required to do: sump, effluent or sewage.
2. Determine voltage of electrical supply for pump.
3. Determine the approx GPM of flow into system using velocity load, velocity is determined with a minimum of 2ft per second flow in order to keep pipeline free. The following is recommended for use.
pipe size 1.5″ – 13GPM
pipe size 2″ – 21GPM
System Load Sizing (as a general rule)
Sump systems: Calculate basement square footage, divide by 100 and then multiplied by 2.50 will equate the GPM (i.e. 500 sq.ft basement will equate to 12.5 GPM) Sewage systems You must add total fixtures (e.g. taps, w/c, bath, shower, washing machine etc) that will drain to the system. Each unit has a value as below: –
Value table
Bath = 2
Dishwasher = 2
Kitchen Sink = 2
W/C = 2
Shower = 2
Unlisted 1.5″ pipe = +3
Unlisted 2″ pipe = +4
Average flow rate for 3/4 bedroom property is approx. 10-12GPM. Estimates vary, but each person uses about 80-100ltr of water per day. Add all fixtures values together and multiply by 0.5 to get an estimated GPM load (e.g. 45 fixtures x 0.5 = 22.5 GPM). The GPM rate needs to be greater than the required velocity in order to keep the pipe free of debris.
Duty stand-by
typically duty stand-by (or 24hr storage) for a sewage pumping station for a 24hr use property is 150ltr per person per day. (for the residential property you do this by bedrooms but doubling up the 1st bedroom)
A 4 bedroom house is classed as 5 people (first room is always classed as 2 people) requiring 150ltr per day per person, you need a minimum of 750ltr chamber for duty stand-by. For offices, classrooms etc (buildings only used by day, this is reduced to 50ltr per person per day. ie an office with 30 people in total would need 1,500ltr
For visitors storage is 5ltr per person (Example: a restaurant with 8 staff and 100 visitors per day would require 8 x 50ltr and 100 x 5ltr = 900ltr storage)
Types of Pump
Sump Pump: A pump to handle water that does not drain by gravity. i.e. basement sumps, car parks, rainwater harvesting, manholes and low land areas.
Effluent Pump: A pump for grey, soiled water, i.e., from septic tanks. up to 3/4″ inch.
Sewage Pump: A pump to handle waste from homes, offices and anywhere with W/C facilities. They are not grinder pumps and should not be used for commercial applications. will not handle sanitary products and products inc nappies, napkins etc.
Pump Sizing
Pump Lift: The vertical lift (dynamic head) it has to pump. measured from the outlet of the pump to its highest pumping within the discharge pipe.
Horizontal Run: distance slows down the liquid within the pump and horizontal run needs to be considered when calculating the overall pump performance.
Pipe Size: The pump discharge size will determine the pipe size. Using pipe that is smaller than the pump discharge will cause friction loss and more back pressure on the pump affecting its performance.
GPM: (Gallons Per Minute) Determine how many gallons per minute the pump needs to remove. under sizing the pumps basin will cause the pump to run more frequent affecting the lifespan of the pump.
This is a general guide as to what type of pumping station you should be looking for but may not be the correct pumping station for your specific job.
Please note, variants of pump power and chamber size can be built to your specific requirements. Please call, we’ll be more than happy to help choose the right kit.
General things to consider when selecting the right pumping stations
1. Building regs (see pumping station sizing guide)
2. Depth of invert
3. Overall pump lift
4. Overall pump distance
5. Pump flow (at final discharge point)
6. Chamber storage capacity
Further dpt options
1. High water alarms
2. Dual pumps
3. Higher lift pumps
4. Manhole cover type
5. Rigid or flexi discharge pipe
6. Sewer connection kit
7. Control panel kiosks
8. SMS texting system
9. Commissioning
10. Servicing