# Keystone Pump TDH Calculator vs PID Controller Simulation

The clearest difference is review sentiment: Keystone Pump TDH Calculator at 100% against PID Controller Simulation's 33%. Keystone Pump TDH Calculator also leads on price (Free vs $3.99) and rating (5.0 vs 3.0). PID Controller Simulation's advantage is device support (3 vs 1) and iOS requirement (13.0 vs 17.6). On ratings volume, update cadence, ads and in-app purchases there is nothing between them.

Keystone Pump TDH Calculator is free to download; PID Controller Simulation costs $3.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Keystone Pump TDH Calculator holds the better App Store score, 5.0 against 3.0. Both are backed by a comparable volume of ratings — 1 and 2 respectively. Written reviews point the same way: 100% of Keystone Pump TDH Calculator's written reviews are positive against 33% of PID Controller Simulation's.

Keystone Pump TDH Calculator ships an update every 6 months, PID Controller Simulation every 3 months. The most recent releases landed on May 31, 2026 and September 23, 2026 respectively.

## The numbers

| Metric | Keystone Pump TDH Calculator | PID Controller Simulation |
| --- | --- | --- |
| Price | **Free** | $3.99 |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/keystone-pump-tdh-calculator/id880925443/reviews)** | [3.0 (2 ratings)](https://appshunter.io/ios/app/pid-controller-simulation/id6612009107/reviews) |
| Number of ratings | 1 | **2** |
| Positive reviews | **100.0% of reviews** | 33.3% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 6 months | **Every 3 months** |
| Monetization | **Free** | Paid |
| Size | 3 MB | 6 MB |
| Requires iOS | 17.6 | **13.0** |
| Devices | iPhone | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Keystone Pumps LTD](https://appshunter.io/developer/435839301) | [立娜 王](https://appshunter.io/developer/1761096632) |

## What reviewers say

### Keystone Pump TDH Calculator

[App page](https://appshunter.io/ios/app/keystone-pump-tdh-calculator/id880925443)

This utility app assists engineers and technical personnel in calculating system parameters for slurry pipe and pump sizing. It computes required head pressure and limiting settling velocity based on user-inputted system data. The tool aims to simplify the selection process for slurry pumps.

**Highlights:** Slurry Density Calculation, Limiting Settling Velocity Calculation, Slurry Head & Equivalent Water Head Calculation, Pipe Type and Size Database, NPSHA Calculation, US and Metric Units, Save Calculation Results

**Features:** macOS Compatibility

**In-app purchases:** none


### PID Controller Simulation

[App page](https://appshunter.io/ios/app/pid-controller-simulation/id6612009107)

Master PID control theory and practice with this comprehensive simulation platform. Learn fundamental concepts, tune parameters, and simulate real-world applications like temperature and motor speed control. Export PID parameters as production-ready code in multiple languages.

**Highlights:** Comprehensive tutorial system, Interactive scenario simulations, Performance analysis tools, Code generator for multiple languages, Real-time curve visualization, Advanced PID algorithm explanations

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is Keystone Pump TDH Calculator free?

Keystone Pump TDH Calculator is free to download, with no in-app purchases.

### Is PID Controller Simulation free?

PID Controller Simulation costs $3.99, with no in-app purchases.

### Which has better reviews, Keystone Pump TDH Calculator or PID Controller Simulation?

Keystone Pump TDH Calculator is rated higher. Keystone Pump TDH Calculator averages 5.0 out of 5 from 1 ratings, while PID Controller Simulation averages 3.0 from 2 ratings.

### Do Keystone Pump TDH Calculator or PID Controller Simulation have ads?

Neither Keystone Pump TDH Calculator nor PID Controller Simulation shows ads.

### Which is updated more often, Keystone Pump TDH Calculator or PID Controller Simulation?

Keystone Pump TDH Calculator ships an update every 6 months, and PID Controller Simulation every 3 months. Most recently, Keystone Pump TDH Calculator was updated on May 31, 2026 and PID Controller Simulation on September 23, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*