Honda WMP20X1 - 220 GPM (2") Chemical-Resistant Pump

That's a hard question to answer Brent and there really isn't a way to gauge it. Run times are based on how easy or how hard the engine is running. If you're pumping a short distance with minimal head lift, you may see about 2 to 3 hours of run time, but if you're pumping very long distances and requiring a lot of lift, that may dwindle to 60 - 90 minutes of run time. You might equate it to how you drive your car? If you accelerate fast and brake the same and often, your gas mileage suffers. It's the same with any gas powered piece of equipment. The harder you work it, the less run time you will realize.
If you have any other questions, please let me know.

Thank you for your interest in Water Pumps Direct. Please see the below list of approved chemicals for the Honda WMP20XA Pump. If you have additional questions on chemicals not listed, please contact Honda tech support at 770-497-6400.

WMP20XA Approved Pumping Applications
Industrial Chemicals

Acetic Acid, 20%
Aluminum Sulfate Ammonium
Nitrate
Ammonium Sulfate
Barium Sulfate
Borax (Sodium Borate)
Calcium Chloride*
Citric Acid
Copper Sulfate
Detergents (general)
Ethylene Glycol
Fatty Acids
Ferric Nitrate
Ferric Sulfate
Ferrous Sulfate
Formaldehyde, 40%
Glycerine (Gycerol)
Lactic Acid
Lead Acetate
Magnesium Chloride
Magnesium Nitrate
Magnesium Sulfate
Maleic Acid
Nickel Chloride
Nickel Sulfate
Oleic Acid
Phosphoric Acid, 0-80%
Potassium Carbonate
Potassium Chloride
Potassium Nitrate
Potassium Sulfate
Soaps (neutral)
Sodium Acetate
Sodium Bicarbonate
Sodium Bisulfate
Sodium Carbonate, 10%
Sodium Chlorate
Sodium Chloride
Sodium Nitrate
Sodium Silicate
Sodium Sulfate
Stearic Acid
Sulfuric Acid, 0-29%
Tartaric Acid
Vinegar
Water (clear)
Water (salt)
Zinc Sulfate
* Temperature does not exceed 27°C (80°F).

Agricultural Chemicals
Aatrex
Amiben
Ammonium Thiosulfate
Avenge
Banvel
Basagran
Bicep
Bladex
Dual
Eradicane
Extrazine
Larsban
Lasso
URAN Solutions
Modown
N-Serve 24
Phosphoric Acid Solutions
Poly-N
Ranger
Round-Up
Sutan
Treflan
Vernam

• Do not use the WMP20XA for pumping liquids for human consumption.
• After each use, drain the pump housing into a suitable container and flush with fresh water.
• The temperature operating range of the pump is between -7 and 54°C (20 and 130°F)

There is no problem installing a ball valve on the discharge to reduce the flow from 220GPM to your required 30GPM.
The only precautions to consider are:
1) Don't completely shut off the flow for more than a couple of minutes because the water will slowly heat up in the pump housing and can eventually get hot enough to cause damage. But simply stopping the flow
(dead-heading) briefly for a short period (a couple of minutes) is no problem. You can restrict the flow as much as you want long term, as long as a small amount is allowed to flow, just to keep the pump cool (even 1 gpm is enough).
2) Never drive over the discharge hose, but this is especially important if a valve is installed at the end of the hose and the pump is dead-headed.
Doing so can force water back into the pump (simple hydraulics) causing damage to the pump.
3) If the valve is installed directly on the pump, it needs to be very light PVC (or similar) without any long sections of pipe between the discharge port and the valve. A heavy valve or a valve rigidly installed using a section of pipe between the valve and the pump may cause the discharge elbow and/or pump housing to break. If the valve is heavy and/or not attached directly on the pump, it's best to run a section of flexible hose between the pump and the valve.
4) And lastly, never install a ball valve on or restrict the suction side of the pump. Doing this can result in cavitation damage.